Profound Lymphopenia Research Articles

P028 Progressive multifocal leukoencephalopathy in a patient with systemic lupus erythematosus

Abstract Background/Aims Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease that develops following the reactivation of the John Cunningham virus (JCV) that in rare circumstances can occur in autoimmune disorders such as systemic lupus erythematosus (SLE). We present a 75-year-old female with SLE who had been treated with immunosuppressive therapy (mycophenylate and steroids) for one year. Methods A 75 year-old female presented with sub-acute deterioration of physical and cognitive function over the course of a few months including memory loss, ataxia, dysgraphia, word finding difficulty, confusion, low mood and reduced oral intake. Neurological examination revealed receptive and expressive aphasia, gaze fixation, unilateral weakness, brisk reflexes with positive plantar reflex and rigidity. A diagnosis of PML was made due to the detection of JC virus in the cerebrospinal fluid (234 copies/ml) and brain MRI findings consistent with the disease. Haematology results showed a profound lymphopenia (0.1x109 ). Mycophenolate was held and she was commenced on increasing doses of Mirtazapine up to 45mg. Clinical review at four months found marked improvement in her cognitive and physical abilities. Repeat CSF analysis found JC virus to be undetectable. Results PML has a 20-fold greater incidence in SLE when compared with the general population. Lymphopenia is a common finding in patients with SLE and has been found to correlate with both the risk and severity of opportunistic infections. The cause of this can be multifactorial and immunosuppressive drugs are often implicated however SLE in isolation can cause severe CD4+ lymphopenia leading to an increased risk of PML reactivation. This case demonstrates the importance of monitoring lymphocyte counts in SLE. Current guidance suggests adjusting regimes of immunosuppressive therapy if lymphocyte counts fall below 1x109 however further guidance on its management may be warranted. The heterogenous manifestation of SLE can make differentiating between the neurological syndromes associated with rheumatic disease and PML challenging. Given the management of PML is vastly different to that of SLE in regards to introduction or withdrawal of immunosuppressive therapies, there should be a high index of clinical suspicion in the early stages of investigation. In vitro studies have explored the possibility of mirtazapine (a 5-HT2A antagonist) providing a low-risk treatment option for those with SLE and this warrants further research into its efficacy in treating or preventing PML in this cohort. Our patient had improved symptomology after cessation of mycophenolate and the commencement of Mirtazapine. Conclusion PML is a rare complication of SLE but should be considered in patients admitted with neuropsychiatric presentations, the use of Mirtazapine may provide a low-risk treatment strategy. Disclosure D. Babla: None. Y. Suleman: None. A. Whittington: None. S. Hamdulay: None.

Emergency Myelopoiesis Distinguishes Multisystem Inflammatory Syndrome in Children From Pediatric Severe Coronavirus Disease 2019.

Multisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory condition caused by recent infection with severe acute respiratory syndrome coronavirus 2, but the underlying immunological mechanisms driving this distinct syndrome are unknown. We utilized high-dimensional flow cytometry, cell-free (cf) DNA, and cytokine and chemokine profiling to identify mechanisms of critical illness distinguishing MIS-C from severe acute coronavirus disease 2019 (SAC). Compared to SAC, MIS-C patients demonstrated profound innate immune cell death and features of emergency myelopoiesis (EM), an understudied phenomenon observed in severe inflammation. EM signatures were characterized by fewer mature myeloid cells in the periphery and decreased expression of HLA-DR and CD86 on antigen-presenting cells. Interleukin 27 (IL-27), a cytokine known to drive hematopoietic stem cells toward EM, was increased in MIS-C, and correlated with immature cell signatures in MIS-C. Upon recovery, EM signatures decreased and IL-27 plasma levels returned to normal levels. Despite profound lymphopenia, we report a lack of cfDNA released by adaptive immune cells and increased CCR7 expression on T cells indicative of egress out of peripheral blood. Immune cell signatures of EM combined with elevated innate immune cell-derived cfDNA levels distinguish MIS-C from SAC in children and provide mechanistic insight into dysregulated immunity contributing toward MIS-C, offering potential diagnostic and therapeutic targets.

Bendamustine Is Less Toxic Than Fludarabine-Cyclophosphamide-Based Lymphodepletion before CD28-Costimulated CART19 through Reduced Inflammatory Cytokines

Introduction: Lymphodepletion (LD) is an integral component of anti-CD19 chimeric antigen receptor T cell (CART19) immunotherapy, creating the proper environment and cytokine milieu for CART engraftment and function. We previously demonstrated that bendamustine (Benda) LD is as effective as standard fludarabine and cyclophosphamide (Flu/Cy) LD prior to 4-1BB-costimulated tisagenlecleucel but is characterized by significantly reduced cytokine-release syndrome (CRS), neurotoxicity (ICANS), and hematological toxicities. However, whether Benda LD is also effective and safe in CD28 costimulated CART19, and the mechanism for the reduced toxicities associated with Benda LD remain unknown. Methods: We retrospectively evaluated the outcomes of 59 consecutive non-Hodgkin lymphoma patients (pts), including large B cell lymphomas (LBCL, n=48) and follicular lymphoma (FL, n=11), treated with commercial CD28 costimulated axicabtagene ciloleucel (axi-cel) at the University of Pennsylvania between January 2018 and March 2023. Data cut-off was June 30 th, 2023. LD regimens were Flu 30 mg/m 2/day and Cy 500 mg/m 2/day x 3 days or Benda 90 mg/m 2/day x 2 days. LD choice was at the treating physician's discretion, partially determined by Flu shortage. Pts were evaluated for 3-month response (Lugano criteria), survival, and toxicities (ASTCT, CTCAE) in the 30 days after axi-cel infusion. For hematological toxicities, we analyzed lymphocyte, neutrophil, platelet, and hemoglobin levels from the first day of LD to 30 days after axi-cel infusion. For long-term hematological toxicities, we retrieved blood values at 6 months in pts with ongoing remission. Moreover, we analyzed serum samples collected pre- and post-LD (CART19 infusion day) for changes in circulating cytokines (Luminex) and metabolites (Liquid Chromatography/Mass Spectrometry) in a second cohort of 32 pts undergoing CART19. Results: Of 59 pts, 37 received Flu/Cy while 22 Benda LD. The two groups were balanced for most clinical features. Responses with Flu/Cy and Benda LD were similar, with complete remission rates of 51.4% and 50.0%, respectively. Progression-free and overall survivals were similar in the two LD groups. However, any-grade CRS occurred in 91.9% of pts who received Flu/Cy versus 72.7% of pts who received Benda LD; any-grade ICANS after Flu/Cy occurred in 43.2% and after Benda LD in 18.2% of pts ( Fig.1A). These results were confirmed in both LBCL and FL cohorts. Both LD regimens induced profound lymphopenia by the time of axi-cel infusion. However, Flu/Cy LD induced a deeper reduction in median lymphocyte counts (Flu/Cy: 0.00x10 9/L; Benda, 0.20x10 9/L). Additionally, Flu/Cy was associated with a higher incidence of neutropenia of grade ≥3 (100.0% vs 54.5%). Consequently, Flu/Cy pts were more likely to develop infections (78.4% vs. 27.3%), and neutropenic fever (78.4% vs. 13.6%) than Benda receiving pts. By evaluating long-term hematological toxicities, 75.0% of Flu/Cy pts did not have lymphocyte recovery to normal values at 6 months compared to 37.5% with Benda LD. Mechanistically, both Flu/Cy (n=7) and Benda (n=25) LD regimens induced an increase in the levels of cytokines facilitating CART proliferation (IL2, IL7, IL15). Overall, Flu/Cy LD pts had a higher increase in inflammatory cytokine levels compared to Benda LD pts, including a higher increase in the levels of cytokines previously associated with CRS and ICANS (IL15, IL8, and MCP1, Fig.1B). Moreover, after LD, several indispensable anabolic metabolites, including carnitine esters, were decreased in pts receiving Flu/Cy. We also found that NADH and nicotinamide riboside, critical elements for cellular redox balance, were reduced in pts exposed to Flu/Cy LD. We speculate that the higher cytotoxicity/cytopenias, induced by Flu/Cy LD, causes a faster utilization of the above-mentioned metabolites in order to reconstitute the hematopoietic cell compartment to physiological levels, resulting in a higher patient susceptibility to additional metabolic stress. Conclusions: In this retrospective comparison,Benda LD is a safer alternative to Flu/Cy for CART19 immunotherapy with similar efficacy and significantly reduced toxicities. Our data can serve as guidance to clinicians for the selection of the best regimen for lymphodepletion. Our conclusions are supported by our mechanistic studies showing reduced inflammatory cytokines after Benda LD.

Loss of Metabolic Control Beyond the Promyelocyte Stage Resolves Myeloid Maturation Arrest in Reticular Dysgenesis

Reticular Dysgenesis (RD) is a particularly grave syndromic form of severe combined immunodeficiency. The hematopoietic phenotype manifests in defective myeloid and lymphoid development with profound neutropenia and lymphopenia. RD is caused by biallelic mutations in the mitochondrial enzyme adenylate kinase 2 (AK2), which catalyzes the phosphorylation of adenosine monophosphate (AMP) to adenosine diphosphate (ADP) in the mitochondrial intermembrane space. ADP is then phosphorylated to adenosine triphosphate (ATP) during the OXPHOS process. While there are abundant other sources of APD, AK2 constitutes the only mitochondrial enzyme that contributes to AMP “recycling” by phosphorylation. Accordingly, AK2-deficient myeloid cells have been shown to exhibit increased AMP levels 1. Beyond this observation, the cellular basis for the combined hematopoietic defect in RD remains elusive. Using a CRISPR/Cas9 AK2 biallelic knock-out model in human hematopoietic stem and progenitor cells (HSPCs), we have previously shown that AK2-/- HSPCs recapitulate RD myelopoiesis defects in vitro. AK2-/- HSPCs exhibit a severe proliferative defect that becomes apparent at the myelocyte (MC) and neutrophil (NP) stages, while the promyelocyte (PM) stage appears relatively spared, consistent with observations in RD patients. Our prior metabolomic analysis showed that AK2-/- MCs not only have increased levels of AMP but up of 20-fold increased levels of IMP derived by converting excess AMP to IMP conversion via AMP deaminases (AMPDs). In addition, we have shown that beginning at the MC stage, AK2 -/- cells exhibit an increase in NADH:NAD+ ratio, consistent with reductive stress and decreased aspartate levels. Our new data revealed that expressing the aspartate transporter GLAST and/or the water-forming NADH oxidase LbNOX in AK2-/- HSPCs partially rescues differentiation but not the proliferation defect. It raises the possibility that reductive stress and aspartate deficiency compromise protein synthesis necessary for maturation, but are separate from the proliferative defect related to high IMP and AMP levels. There were no metabolomic abnormalities noted at the PM stage. PMs have a higher proliferative index than MCs and NPs. This raises the question why the most metabolically active stage is phenotypically spared by AK2 deficiency. To better understand why the metabolic abnormalities associated with RD selectively affect differentiation beyond the promyelocyte stage, we investigated key regulators of cellular metabolism and proliferation, i.e., AMPK, ACC1 and S6, a target of mTOR signaling, at PM, MC and NP stages. We found activation of AMPK, ACC1 and S6 only at the PM stage, while AMPK, ACC1 and S6 protein expression at MC and NP stages was virtually undetectable. Interestingly, AK2-/- PMs exhibited notably lower ATP synthesis rates compared to controls, while ATP synthesis in AK2-/- MCs and NPs was significantly higher than in controls of corresponding stages, paralleling the accumulation of AMP and IMP noted earlier. These findings raise the possibility that tight metabolic control at the promyelocyte stage prevents AMP levels from rising by curtailing OXPHOS metabolism in AK2-/- PMs. In contrast, lack of metabolic control beyond the PM stage permits unopposed OXPHOS activity, thereby allowing AMP and IMP levels to rise to toxic levels that interfere with proliferation. In our ongoing work, we are testing whether pharmacologically redirecting metabolism from OXPHOS to glycolysis with UK5099, could rescue AK2-/- myelopoiesis defects. UK5099 is a potent inhibitor of the mitochondrial pyruvate carrier, which facilitates pyruvate transport across the mitochondrial inner membrane to fuel the TCA cycle. Additionally, we developed a hematopoietic-specific and inducible Cre-mediated Ak2 knock-out mouse model, which recapitulates the profound neutropenia and lymphopenia observed in RD patients. This mouse model will allow us to corroborate our in vitro observations and to investigate if the same mechanistic underpinnings also apply to the lymphoid lineage. Rissone A, Weinacht KG, la Marca G, et al. Reticular dysgenesis-associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress. J Exp Med. Jul 27 2015;212(8):1185-202. doi:10.1084/jem.20141286

Foxn1 is not essential for T-cell development in teleosts.

In mammals, T-cell development depends on the activity of the Foxn1 transcription factor in the thymic epithelium; mutations in the vertebrate-specific Foxn1 gene are associated with profound T-cell lymphopenia and fatal immunodeficiency. Here, we examined the extent of T-cell development in teleosts lacking a functional foxn1 gene. In zebrafish carrying a deleterious internal deletion of foxn1, reduced but robust lymphopoietic activity is maintained in the mutant thymus. Moreover, pseudogenization or loss of foxn1 in the genomes of deep-sea anglerfishes is independent of the presence or absence of the canonical signatures of the T-cell lineage. Thus, in contrast to the situation in mammals, the teleost thymus can support foxn1-independent lymphopoiesis, most likely through the activity of the Foxn4, an ancient metazoan paralog of Foxn1. Our results imply that during the early stages of vertebrate evolution, genetic control of thymopoiesis was functionally redundant and thus robust; in mammals, the genetic network was reorganized to become uniquely dependent on the FOXN1 transcription factor.

Whole exome sequencing reveals a missense mutation in the ADA gene causing severe combined immune deficiency in a Pakistani family ADA gene mutation causing SCID

BACKGROUND & OBJECTIVE: Human adenosine deaminase deficiency, OMIM 102700 (ADA deficiency) is a genetic disorder which causes severe combined immunodeficiency (SCID). The enzyme adenosine deaminase is a housekeeping in nature and is involved in purine catabolism by catalyzing irreversible deamination of adenosine and deoxyadenosine. The SCID patients’ immune system is unable to fight off most of the bacterial and fungal infections due to profound lymphopenia (T-B-NK+). About 20% of the SCID patients are genetically homozygous for defective ADA gene. In our study we aimed to find out genetic variant in ADA gene in a family carrying severe combined immune deficiency. Objective in the current study is to unravel and characterize the molecular cause of the patient suffering from by birth SCID.
 METHODOLOGY: In the present study we enrolled a 6-month-old female SCID patient belonging to highly consanguineous Pakistani family. Patient clinical features included repeated chest infection with failure to thrive, fever and chronic diarrhea. Whole blood samples from patient, parents and healthy siblings were acquired in EDTA tubes. DNA was extracted from all the blood samples.
 RESULTS: Flowcytometry revealed lymphopenia (T-B-NK+) type of SCID. Whole Exome Sequencing (WES) identified a one nucleotide change (c.716G>A) in ADA gene exon 8. The segregation of the identified variant in the family was confirmed through Sanger Sequencing.
 CONCLUSION: In this study, we presented detailed clinical and genetic description of patient suffering from severe combined immune deficiency. The immunological and genetic findings presented in this study will facilitate early diagnosis of the disease. Segregation of the identified variant in the family members will also aid in genetic counseling the family.

Brain resident memory T cells rapidly expand and initiate neuroinflammatory responses following CNS viral infection

The contribution of circulating verses tissue resident memory T cells (TRMs) to clinical neuropathology is an enduring question due to a lack of mechanistic insights. The prevailing view is TRMs are protective against pathogens in the brain. However, the extent to which antigen-specific TRMs induce neuropathology upon reactivation is understudied. Using the described phenotype of TRMs, we found that brains of naïve mice harbor populations of CD69+ CD103- T cells. Notably, numbers of CD69+ CD103- TRMs rapidly increase following neurological insults of various origins. This TRM expansion precedes infiltration of virus antigen-specific CD8 T cells and is due to proliferation of T cells within the brain. We next evaluated the capacity of antigen-specific TRMs in the brain to induce significant neuroinflammation post virus clearance, including infiltration of inflammatory myeloid cells, activation of T cells in the brain, microglial activation, and significant blood brain barrier disruption. These neuroinflammatory events were induced by TRMs, as depletion of peripheral T cells or blocking T cell trafficking using FTY720 did not change the neuroinflammatory course. Depletion of all CD8 T cells, however, completely abrogated the neuroinflammatory response. Reactivation of antigen-specific TRMs in the brain also induced profound lymphopenia within the blood compartment. We have therefore determined that antigen-specific TRMs can induce significant neuroinflammation, neuropathology, and peripheral immunosuppression. The use of cognate antigen to reactivate CD8 TRMs enables us to isolate the neuropathologic effects induced by this cell type independently of other branches of immunological memory, differentiating this work from studies employing whole pathogen re-challenge. This study also demonstrates the capacity for CD8 TRMs to contribute to pathology associated with neurodegenerative disorders and long-term complications associated with viral infections. Understanding functions of brain TRMs is crucial in investigating their role in neurodegenerative disorders including MS, CNS cancers, and long-term complications associated with viral infections including COVID-19.

Allogeneic, donor-derived, second-generation, CD19-directed CAR-T cells for the treatment of pediatric relapsed/refractory BCP-ALL

AbstractAutologous CD19-directed chimeric antigen receptor (CAR)-T cells have shown unprecedented efficacy in children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, patients either relapsing after allogeneic hematopoietic stem cell transplantation (allo-HSCT) or displaying profound lymphopenia and/or rapidly progressing disease often cannot access autologous products. These hurdles may be overcome by allogeneic, donor-derived CAR-T cells. We tested donor-derived T cells transduced with a second-generation (4.1BB) CD19-directed CAR for treatment of patients with BCP-ALL in a hospital-exemption setting. Two constructs were tested: a retroviral construct incorporating the suicide gene inducible caspase-9 (CD19-CAR–Retro_ALLO) first and then a lentiviral construct and an automated, Prodigy-based manufacturing process (CD19-CAR–Lenti_ALLO). Thirteen children/young adults received ALLO–CAR-T cells between March 2021 and October 2022. Doses ranged between 1.0 × 106 and 3.0 × 106 CAR-T cells per kg. The toxicity profile was comparable with that of autologous CAR-T cells, characterized mainly by cytopenia, cytokine release syndrome (maximum grade 1), and grade 2 immune-effector cell–associated neurotoxicity syndrome. One case of acute graft-versus-host disease (GVHD) occurred and was rapidly controlled with steroids and ruxolitinib. None of the other patients, including 3 given ALLO–CAR-T cells from an HLA-haploidentical donor, experienced GVHD. Two patients received ALLO–CAR-T cells before HSCT and showed a significant expansion of CAR-T cells without any sign of GVHD. All patients obtained complete remission (CR) with absence of minimal residual disease in the bone marrow. With a median follow-up of 12 months (range, 5-21), 8 of 13 patients maintained CR. Allogeneic anti-CD19 CAR-T cells can effectively treat highly refractory BCP-ALL relapsing after allo-HSCT without showing increased toxicity as compared with autologous CAR-T cells.

A Case of X-Linked Moesin-Associated Immune Deficiency in a Pediatric Patient

BackgroundX-Linked Moesin-Associated Immune Deficiency (X-MAID) is a rare severe combined immunodeficiency (SCID) subtype that can present at any age due to its variability. Depending on severity, patients demonstrate failure to thrive, recurrent bacterial and viral infections, and increased susceptibility to varicella zoster. It has been characterized by marked lymphopenia with hypogammaglobulinemia and impaired T-cell migration and proliferation. Case PresentationThis is a report of a Cuban 7-year-old male with poor weight gain and facial dysmorphia. He had a history of recurrent bacterial gastrointestinal infections and pneumonia beginning at 4 months of age. He additionally had 4–6 upper respiratory tract and ear infections annually. While still living in Cuba, he was admitted for a profound EBV infection in the setting of significant leukopenia. A bone marrow biopsy confirmed no malignancy. After he moved to the United States, his laboratory work-up revealed marked leukopenia with low absolute neutrophil and lymphocyte count with low T and B cells, very low immunoglobulin levels IgG, IgA, and IgM, and poor vaccination responses to streptococcus pneumonia, varicella zoster, and SARS-CoV-2. Genetic testing revealed a missense pathogenic variant c.511C>T (p.Arg171Trp) in the moesin (MSN) gene associated with X-MAID. He was managed with Bactrim and acyclovir prophylaxis, and immunoglobulin replacement therapy, and considered for hematopoietic stem cell transplantation. DiscussionDiagnosis of X-MAID should be considered in patients with recurrent infections and profound lymphopenia. As with SCID, early diagnosis and intervention is of utmost importance to prevent morbidity and mortality. This case demonstrates the importance of genetic testing in identifying this disease as it may prompt an immunologist to consider HSCT if conservative management is suboptimal. In the current literature, HSCT appears promising, but the long-term outcomes have yet to be described.

Early immune reconstitution in an infant with adenosine deaminase deficient severe combined immunodeficiency started on enzyme replacement therapy

Severe Combined Immunodeficiency (SCID) due to adenosine deaminase (ADA) deficiency is an inborn error of immunity resulting in the accumulation of adenosine and deoxyadenosine leading to a T-B-NK-phenotype. Enzyme Replacement Therapy with Elapegademase-IvIr is typically used as a bridge prior to undergoing definitive treatment with HSCT or HSC-GT.We report a full-term female infant born to Caucasian parents. Immediate newborn course was unremarkable. She had two borderline newborn screens (NBS) for SCID. There was no consanguinity or family history of immunodeficiency. Physical exam was normal except for absent tonsils. She had profound lymphopenia (Absolute Lymphocyte Count of 210 cells/mL), and initial lymphocyte enumeration showed low CD3 cells (169/mL), decreased CD19 cells (6/mL) and CD16/56+ cells (26/mL) consistent with a T-B-NK- SCID. There was no maternal engraftment. Immunoglobulin studies showed normal IgG (325) with low IgM and IgA. Mitogen proliferation to phytohemagglutinin (PHA) was significantly low (10,200 CPM).A SCID genetics panel revealed two pathogenic variants in ADA (p.Glu319fs and p.Arg149Trp). Biochemical testing confirmed absent ADA activity and elevated total deoxyadenosine nucleotides (dAXP) of 40.3% in RBCs (normally undetectable), consistent with the diagnosis of ADA-SCID. She was promptly started on ERT twice weekly and developed full immune reconstitution of her T-cells, B-cells and NK-cells after 21 days. At that time, her dAXP remained elevated at 10%. Her T-cell function also normalized (PHA 239,562 CPM).We report an infant with ADA-SCID who had two borderline NBS results and developed full immune reconstitution 3 weeks after starting ERT. This is unusual since thymopoiesis typically requires 60–90 days for T-cell reconstitution. While B and NK immune reconstitution typically occurs early, early T-cell numbers lag behind, especially while dAXP levels remain measurable. Both genetic variants in this patient are severe, but somatic mosaicism with reversion of the Arg149Trp point mutation might account for rapid T-cell recovery; further T-cell analysis is planned to assess this possibility. This child is the first case of SCID diagnosed in North Carolina following a borderline NBS, as opposed to abnormal, reinforcing the utility of highly-sensitive TREC thresholds for identification of at-risk infants. [Display omitted] [Display omitted]

A baby girl with TBX1 haploinsufficiency who died after elective cardiac repair surgery due to suspected enteroviral meningitis

IntroductionTBX1 haploinsufficiency is an inborn error of immunity with the phenotype of DiGeorge Syndrome. DiGeorge Syndrome has variable immunodeficiency associated with grade of thymic hypoplasia ranging from mild with no infections to severe requiring thymus implant. Enterovirus is an example of an opportunistic infection that can be fatal in these patients. Case PresentationA 1 year old girl with TBX1 haploinsufficiency complicated by Tetralogy of Fallot, pulmonary atresia, high arched palate, and vesicovaginal fistula presented for elective cardiac repair surgery from another country due to failure to thrive and cyanosis. She had no prior infectious history but was on sulfamethoxazole-trimethoprim for prophylaxis. She was asymptomatic with a negative COVID test but no other infectious studies performed. Immediately postoperatively, she was febrile and nasal respiratory viral panel was positive for rhinovirus/enterovirus with increased procalcitonin and leukocytosis with left shift. She decompensated with multi-organ failure and cardiac arrest on postoperative day two. She was cannulated to veno-arterial extracorporeal membrane oxygenation (ECMO). Pre-operatively, she had a normal absolute lymphocyte count. No thymus tissue was observed in surgery. She had profound CD3 lymphopenia to 130 cells/cmm when critically ill. Enteroviral meningitis was suspected as no infectious, cardiac, or other pathology could be identified causing decompensation. Enteroviral serum polymerase chain reaction (PCR) test was negative while lumbar puncture deferred due to clinical status. She was treated with immunoglobulin. Offlabel investigational drug pocapavir was considered but deferred to patient’s irreversible neurological status. The patient was disconnected from ECMO and expired. DiscussionThough we cannot confirm that this patient had enteroviral meningitis, invasive enteroviral infections are associated with elevated transaminases, coagulopathy, and seizures all present in our patient. There has also been reported negative serum enteroviral PCR but positive CSF enteroviral PCR in an immunodeficient patient. Additionally, this case highlights the importance of immunologic evaluation in patients with DiGeorge Syndrome and questions if asymptomatic viral screening for viruses like enterovirus should be considered pre-operatively in patients with inborn errors of immunity. This case highlights potential treatment options for invasive enteroviral infections in patients with inborn errors of immunity: high dose immunoglobulin, fluoxetine, and pocapavir.

Mucormycosis in this COVID times- A case series

Mucorales are fast-growing thermostat fungi that are ubiquitous in environment. Most common form is rhino-orbito-cerebral mucormycosis. It is the third most common cause of invasive fungal infections following asperigillosis and candidiasis. Their incidence has increased in recent times, especially in the 2 wave of COVID-19 in India. COVID-19 is caused by non-segmented negative sense RNA virus, which causes profound lymphopenia. Glucocorticoid has emerged as main treatment of choice for COVID-19 patients with severe symptoms. The patients of COVID-19 are increasingly affected with mucormycosis because of decreased immunity, impaired defense mechanisms, dysfunctional lymphocytes and neutrophils, and injudicious use of glucocorticoids. Diabetes mellitus is an independent risk factor for both mucormycosis and severe COVID-19. Hyperglycemia due to diabetes and glucocorticoid increases the incidence of infection due to greater availability of glucose to the pathogen, lower response of T cells, and acidic Ph. This fungus has predilection to invade blood vessels leading to extensive necrosis (black eschar). The overall mortality rate is 56%. Mortality depends upon underlying health condition of patient and the part of the body affected.In this retrospective study, we present an interesting case series of 15 patients with mucormycosis. Association with diabetes, with uncontrolled glycemic index was found in all the cases. COVID-19 associated mucormycosis was seen in 10 patients.Excessive use of corticosteroid in a patient with COVID-19 has aggravated the scenario. An early foresight about the condition and judicious use of steroids is useful. So, an early diagnosis and prompt treatment of mucormycosis can decrease the fatality and morbidity in patients.

Late Onset Combined Immune Deficiency (LOCID) Revealed by a Haemolytic Anaemia in a Child: A Case Report

Variable Common Immune Deficiency (VCID) is a very heterogeneous condition both clinically and immunologically. It is a group of molecular abnormalities responsible for a defect in antibody production leading to hypogammaglobulinemia often associated with autoimmune and/or lymphoproliferative manifestations. Late Onset Combined Immune Deficiency (LOCID) is a type of Variable Common Immune Deficiency (VCID) defined by a defect in antibody production (IgG and IgA ± IgM type), profound CD4 T-cell lymphopenia and frequent opportunistic infections. LOCID has been considered as a distinct entity from VCID due to its particular clinical and immunological profile.

Inflammatory profile of convalescent plasma to treat COVID: Impact of amotosalen/UVA pathogen reduction technology.

Blood products in therapeutic transfusion are now commonly acknowledged to contain biologically active constituents during the processes of preparation. In the midst of a worldwide COVID-19 pandemic, preliminary evidence suggests that convalescent plasma may lessen the severity of COVID-19 if administered early in the disease, particularly in patients with profound B-cell lymphopenia and prolonged COVID-19 symptoms. This study examined the influence of photochemical Pathogen Reduction Treatment (PRT) using amotosalen‐HCl and UVA light in comparison with untreated control convalescent plasma (n= 72 – paired samples) - cFFP, regarding soluble inflammatory factors: sCD40L, IFN-alpha, IFN-beta, IFN-gamma, IL-1 beta, IL-6, IL-8, IL-10, IL-18, TNF-alpha and ex-vivo inflammatory bioactivity on endothelial cells. We didn’t observe significant modulation of the majority of inflammatory soluble factors (8 of 10 molecules tested) pre- or post-PRT. We noted that IL-8 concentrations were significantly decreased in cFFP with PRT, whereas the IL-18 concentration was increased by PRT. In contrast, endothelial cell release of IL-6 was similar whether cFFP was pre-treated with or without PRT. Expression of CD54 and CD31 in the presence of cFFP were similar to control levels, and both were significant decreased in when cFFP had been pre-treated by PRT. It will be interesting to continue investigations of IL-18 and IL-8, and the physiopathological effect of PRT- treated convalescent plasma and in clinical trials. But overall, it appears that cFFP post-PRT were not excessively pro-inflammatory. Further research, including a careful clinical evaluation of CCP-treated patients, will be required to thoroughly define the clinical relevance of these findings.

Abstract 10 Interim Results of a Phase I Study Investigating a Cord Blood-Derived Natural Killer Cell Therapy for Patients Hospitalized with COVID-19

IntroductionIn the setting of viral infections, including infection with SARS-CoV-2, lymphocyte exhaustion and lymphopenia are common. Patients with COVID-19 who develop lymphopenia, particularly low numbers of circulating natural killer (NK) cells, are at high risk for disease progression. Thus, strategies that overcome profound lymphopenia and restore innate immune function may reduce the severity of COVID-19. One approach is the direct infusion of an exogenous source of healthy, functional NK cells intended to boost the patient’s immune system during the viral infection, enabling elimination of infected cells. “DVX201” is a cord blood-derived allogeneic NK cell therapy that is cryopreserved and intended for “off-the-shelf use” without HLA-matching.ObjectiveThe primary objective of this study is to investigate the safety and to identify the recommended phase II dose and/or the maximum tolerated dose (MTD) of DVX201 in patients hospitalized with COVID-19.MethodsWe are conducting an open-label, nonrandomized phase I safety and dose-finding (modified 3+3) study of DVX201 at three dose levels in patients hospitalized with COVID-19. Adult patients with documented SARS-CoV-2 infection were eligible if they were admitted to the hospital, were receiving ≤6 L supplemental oxygen by low flow delivery, and did not have other evidence of cytokine storm based on levels of serum IL-6, C-reactive protein, and ferritin.ResultsTo date, 9 patients have been enrolled: 3 subjects at each dose level. All dose levels have been well tolerated, with no dose-limiting toxicities, infusion toxicities, or cytokine release syndrome observed. All patients were discharged from the hospital at an average of 5 days post infusion. Blood samples were drawn for correlative studies including persistence of DVX201, pre- and post-infusion immune system characterization, and cytokine panels. Accrual is continuing at the MTD.DiscussionThis trial will serve as the proof of concept for the use of DVX201 as an anti-viral treatment for COVID-19. These results will inform the potential role of DVX201 for treatment of other life-threatening viral infections by harnessing NK cells’ innate function to kill virally infected cells, regardless of the etiology of the infection.

Limited impact of fingolimod treatment during the initial weeks of ART in SIV-infected rhesus macaques

Antiretroviral therapy (ART) is not curative due to the persistence of a reservoir of HIV-infected cells, particularly in tissues such as lymph nodes, with the potential to cause viral rebound after treatment cessation. In this study, fingolimod (FTY720), a lysophospholipid sphingosine-1-phosphate receptor modulator is administered to SIV-infected rhesus macaques at initiation of ART to block the egress from lymphoid tissues of natural killer and T-cells, thereby promoting proximity between cytolytic cells and infected CD4+ T-cells. When compared with the ART-only controls, FTY720 treatment during the initial weeks of ART induces a profound lymphopenia and increases frequencies of CD8+ T-cells expressing perforin in lymph nodes, but not their killing capacity; FTY720 also increases frequencies of cytolytic NK cells in lymph nodes. This increase of cytolytic cells, however, does not limit measures of viral persistence during ART, including intact proviral genomes. After ART interruption, a subset of animals that initially receives FTY720 displays a modest delay in viral rebound, with reduced plasma viremia and frequencies of infected T follicular helper cells. Further research is needed to optimize the potential utility of FTY720 when coupled with strategies that boost the antiviral function of T-cells in lymphoid tissues.

Early administration of remdesivir plus convalescent plasma therapy is effective to treat COVID-19 pneumonia in B-cell depleted patients with hematological malignancies

Patients with hematological malignancies (HMs) are at a higher risk of developing severe form and protracted course of COVID-19 disease. We investigated whether the combination of viral replication inhibition with remdesivir and administration of anti-SARS-CoV-2 immunoglobulins with convalescent plasma (CP) therapy might be sufficient to treat B-cell-depleted patients with COVID-19. We enrolled 20 consecutive patients with various HMs with profound B-cell lymphopenia and COVID-19 pneumonia between December 2020 and May 2021. All patients demonstrated undetectable baseline anti-SARS-CoV-2 immunoglobulin levels before CP. Each patient received at least a complete course of remdesivir and at least one unit of CP. Previous anti-CD20 therapy resulted in a more prolonged SARS-CoV-2 PCR positivity compared to other causes of B-cell lymphopenia (p = 0.004). Timing of CP therapy showed a significant impact on the clinical outcome. Simultaneous use of remdesivir and CP reduced time period for oxygen weaning after diagnosis (p = 0.017), length of hospital stay (p = 0.007), and PCR positivity (p = 0.012) compared to patients who received remdesivir and CP consecutively. In addition, time from the diagnosis to CP therapy affected the length of oxygen dependency (p < 0.001) and hospital stay (p < 0.0001). In those cases where there were at least 10 days from the diagnosis to plasma administration, oxygen dependency was prolonged vs. patients with shorter interval (p = 0.006). In conclusion, the combination of inhibition of viral replication with passive immunization was proved to be efficient and safe. Our results suggest the clear benefit of early, combined administration of remdesivir and CP to avoid protracted COVID-19 disease among patients with HMs and B-cell lymphopenia.

65-Year-Old Man With Weight Loss and Dyspnea on Exertion

65-Year-Old Man With Weight Loss and Dyspnea on Exertion

PB2276: EARLY ADMINISTRATION OF REMDESIVIR PLUS CONVALESCENT PLASMA THERAPY IS EFFECTIVE TO TREAT COVID-19 PNEUMONIA IN B-CELL DEPLETED PATIENTS WITH HEMATOLOGICAL MALIGNANCIES

Background: Patients with hematological malignancies are at a higher risk of developing severe form and protracted course of COVID-19. Remdesivir, an inhibitor of RNA polymerase was identified early as a promising therapeutic regimen for COVID-19, while convalescent plasma (CP) therapy with anti-SARS-CoV-2 antibodies can aid the treatment of COVID-19 in B-cell depleted patients. Aims: Here we investigated whether the combination of externally administered immunoglobulins (Ig) via CP therapy and specific inhibition of viral replication might be sufficient to effectively treat B-cell depleted patients with COVID-19. Methods: We enrolled a series of 20 consecutive patients who suffered from various hematological malignancies with profound B-cell lymphopenia and COVID-19 pneumonia between December 2020 and May 2021. These patients demonstrated a profound B-cell lymphopenia based on flow cytometry analysis of peripheral blood lymphocyte subpopulations. Consequently, they showed undetectable baseline anti-SARS-CoV-2 Ig levels before CP therapy according to anti-SARS-CoV-2 nucleocapsid- and S1-RBD-specific total Ig tests. Each patient received a complete course of remdesivir and at least one unit (200 ml) of AB0 compatible convalescent plasma during their treatment for COVID-19. Results: Previous anti-CD20 therapy resulted in a more prolonged SARS-CoV-2 PCR positivity compared to other causes of B-cell lymphopenia (p=0.004). Timing of CP therapy showed a significant impact on the clinical outcome. Simultaneous use of remdesivir and CP reduced time period for oxygen weaning after diagnosis (p=0.017), length of hospital stay (p=0.007), and PCR positivity (p=0.012) compared to patients who received remdesivir and CP consecutively. In addition, time from the diagnosis to CP therapy affected the length of oxygen dependency (p<0.001) and hospital stay (p<0.0001). In those cases where there were at least ten days from the diagnosis to plasma administration, oxygen dependency was prolonged vs. patients with shorter interval (p<0.001). Summary/Conclusion: Via combined administration of remdesivir and CP, we experienced an overwhelming survival rate in COVID-19 patients with hematological malignancies. Inhibition of viral replication with passive immunization proved to be efficient and safe. Our results suggest the clear benefit of early administration of CP to avoid protracted COVID-19 disease in patients with B-cell lymphopenia.

Bendamustine is safe and effective for lymphodepletion before tisagenlecleucel in patients with refractory or relapsed large B-cell lymphomas

Anti-CD19 chimeric antigen receptor T-cell immunotherapy (CAR-T) is now a standard treatment of relapsed or refractory B-cell non-Hodgkin lymphomas; however, a significant portion of patients do not respond to CAR-T and/or experience toxicities. Lymphodepleting chemotherapy is a critical component of CAR-T that enhances CAR-T-cell engraftment, expansion, cytotoxicity, and persistence. We hypothesized that the lymphodepletion regimen might affect the safety and efficacy of CAR-T. We compared the safety and efficacy of lymphodepletion using either fludarabine/cyclophosphamide (n= 42) or bendamustine (n= 90) before tisagenlecleucel in two cohorts of patients with relapsed or refractory large B-cell lymphomas treated consecutively at three academic institutions in the United States (University of Pennsylvania, n= 90; Oregon Health & Science University, n= 35) and Europe (University of Vienna, n= 7). Response was assessed using the Lugano 2014 criteria and toxicities were assessed by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 and, when possible, the American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading. Fludarabine/cyclophosphamide led to more profound lymphocytopenia after tisagenlecleucel infusion compared with bendamustine, although the efficacy of tisagenlecleucel was similar between the two groups. We observed significant differences, however, in the frequency and severity of adverse events. In particular, patients treated with bendamustine had lower rates of cytokine release syndrome and neurotoxicity. In addition, higher rates of hematological toxicities were observed in patients receiving fludarabine/cyclophosphamide. Bendamustine-treated patients had higher nadir neutrophil counts, hemoglobin levels, and platelet counts, as well as a shorter time to blood count recovery, and received fewer platelet and red cell transfusions. Fewer episodes of infection, neutropenic fever, and post-infusion hospitalization were observed in the bendamustine cohort compared with patients receiving fludarabine/cyclophosphamide. Bendamustine for lymphodepletion before tisagenlecleucel has efficacy similar to fludarabine/cyclophosphamide with reduced toxicities, including cytokine release syndrome, neurotoxicity, infectious and hematological toxicities, as well as reduced hospital utilization.