CD8 T-cell Populations Research Articles

Suboptimal Immune Reconstitution among HIV-Infected Saudi Patients following Successful Antiretroviral Treatment.

Background and Objectives Variations in immune reconstitution following antiretroviral treatment (ART) among HIV patients have previously been observed. This study aims at assessing immune reconstitution after successful ART among HIV-infected Saudi patients. Methods This retrospective study of 240 HIV-infected patients was performed between May 2010 and June 2015 in the HIV center at King Saud Hospital, Riyadh. Data were extracted for CD4, CD8 cell, and CD3/HLA-DR counts along with the viral load from patient records before and after four years of successful ART. The inclusion criterion was patients with CD4 reconstitution of either equal to or more than 400 cells/mm3 with an undetectable HIV viral load following ART. Based on their presentation, the HIV patients were grouped into early treatment (ET) and delayed treatment (DT) groups with CD4 counts of 200–350 cells/mm3 and less than 200 cells/mm3, respectively. Findings The pretreatment CD8+ counts of median 865 cells/mm3 (interquartile range (IQR) 774–1072) in the DT group declined to median 753 cells/mm3 (IQR 574–987; p < 0.0001). Moreover, there was a decline in CD8 counts from 703 cells/mm3 (IQR 655–747) to 620 cells/mm3 (IQR 563–645; p < 0.04) in the ET group after four years of successful ART. Pretreatment activation marker (CD3/HLA-DR+) expression of median 29% in the DT group declined to 22% and in the ET group from a median of 23% to 19% after treatment. The CD4/CD8 ratio in the DT group increased from 0.14 (IQR 0.09–0.88) to 0.71 (IQR 0.54–0.9) and from 0.42 (IQR 0.35–0.55) to 0.87 (IQR 0.71–0.98) in the ET group. Conclusion Immune reconstitution after successful ART among HIV-infected Saudi patients was associated with a CD8 T-cell population expansion with a suboptimal CD4/CD8 ratio and persistent immune activation. Early initiation of ART appears to favorably influence the CD4/CD8 ratio.

Germinal center humoral autoimmunity independently mediates progression of allograft vasculopathy

The development of humoral autoimmunity following organ transplantation is increasingly recognised, but of uncertain significance. We examine whether autoimmunity contributes independently to allograft rejection.In a MHC class II-mismatched murine model of chronic humoral rejection, we report that effector antinuclear autoantibody responses were initiated upon graft-versus-host allorecognition of recipient B cells by donor CD4 T-cells transferred within heart allografts. Consequently, grafts were rejected more rapidly, and with markedly augmented autoantibody responses, upon transplantation of hearts from donors previously primed against recipient. Nevertheless, rejection was dependent upon recipient T follicular helper (TFH) cell differentiation and provision of cognate (peptide-specific) help for maintenance as long-lived GC reactions, which diversified to encompass responses against vimentin autoantigen. Heart grafts transplanted into stable donor/recipient mixed haematopoietic chimeras, or from parental strain donors into F1 recipients (neither of which can trigger host adaptive alloimmune responses), nevertheless provoked GC autoimmunity and were rejected chronically, with rejection similarly dependent upon host TFH cell differentiation.Thus, autoantibody responses contribute independently of host adaptive alloimmunity to graft rejection, but require host TFH cell differentiation to maintain long-lived GC responses. The demonstration that one population of helper CD4 T-cells initiates humoral autoimmunity, but that a second population of TFH cells is required for its maintenance as a GC reaction, has important implications for how autoimmune-related phenomena manifest.

630. Identification of a Depressed Mucosal Immune Environment in HIV Infection

BackgroundAmong patients with human immunodeficiency virus (HIV), pulmonary complications are a common cause of morbidity and mortality. Emerging evidence suggests that respiratory viruses contribute to this disease burden. Although HIV is known to alter other mucosal surfaces including the GI tract and vagina, its effect on the upper respiratory mucosa, the primary target of respiratory viruses, has not been well described. We sought to characterize the effect of HIV on the upper respiratory mucosal immune environment. MethodsTen HIV-infected patients and 10 sex-matched uninfected controls were enrolled. Subjects were ages 18–49, nonsmokers, and otherwise healthy. HIV-infected subjects had complete viral load suppression for at least 6 months prior to participation. Subjects provided serum samples and underwent nasal mucosal sampling procedures—epithelial lining fluid (ELF) collection, nasal lavage (NLF) and nasal biopsy. Serum, ELF, and NLF were analyzed using ELISAs targeted at pro-inflammatory cytokines. NLF was analyzed by flow cytometry for nasal-specific immune cells. ResultsT-cells in NLF, including both CD8 and CD4 populations, were significantly decreased in HIV-infected compared with uninfected subjects. We also found decreased numbers of neutrophils. Additionally, we identified diminished levels of IL-16 in ELF, a T-cell chemoattractant in HIV-infected subjects; however, all other cytokines and chemokines were similar between the two groups. These findings were in contrast to an earlier study we had done in six HIV-infected men with variable levels of HIV control and age-matched control subjects which also demonstrated decreased levels of other pro-inflammatory cytokines, including IL-Iβ, IL-8, and IL-5 in those with HIV.ConclusionThe mechanism underlying the morbidity and mortality of respiratory viruses in HIV-infected patients is unclear. However, we identified that HIV infection does result in relative upper respiratory immune suppression, including in both CD4 and CD8 T-cell populations, despite otherwise excellent systemic control of HIV. We hypothesize that this suppression persists in viral infection leading to an impaired immune response and prolonged respiratory virus replication, contributing to the observed burden of disease in this population. Disclosures All authors: No reported disclosures.

Red blood cell distribution width as an easily measurable biomarker of persistent inflammation and T cell dysregulation in antiretrovirally treated HIV-infected adults

Background: Chronic inflammation and immune dysfunction occur in human immunodeficiency virus (HIV)-infection despite stable antiretroviral therapy (ART). Red blood cell distribution width (RDW) has been shown to correlate with markers of inflammation in non-HIV conditions. The study objective was to determine associations between RDW with cellular markers of immune activation and immune dysfunction including soluble inflammatory mediators in ART treated HIV infection.Methods: We performed a cross-sectional analysis of the Hawaii Aging with HIV-Cardiovascular study. RDW was defined as one standard deviation of RBC size divided by mean corpuscular volume multiplied by 100%. Correlations were analyzed between RDW, soluble inflammatory biomarkers and T cell activation (CD38 + HLA-DR+), senescence (CD28-CD57+), and immune exhaustion (PD-1, TIGIT, TIM-3 expression).Results: Of 158 participants analyzed, median age was 50 years, duration of ART 12.6 years, virally suppressed 84.4%, and CD4 count 503 cells/mm3. Significant positive correlations were identified between RDW and soluble biomarkers including sICAM, IL-8, IL-6, SAA, TNF-α, sE-selection, fibrinogen, D-dimer, CRP, CD4/CD8 ratio, and frequency of multiple CD8 T-cell populations such as CD38 + HLA-DR + T-cells, single TIGIT+, and dual expressing of TIGIT + PD1+, TIGIT + TIM3+, and TIM3 + PD1+ CD8+ T-cell subsets (p < .05). Frequencies of CD38 + HLA-DR + CD8+ T-cells and TIGIT + CD8+ T-cells remained significant adjusting for baseline variables (p < .01).Conclusion: Our study revealed correlations between RDW with systemic inflammatory biomarkers and CD8+ T-cell populations related to immune activation and exhaustion in HIV-infected individuals on ART. Further studies are warranted to determine the utility of RDW as a marker of immune dysregulation in HIV.

CD4 T cell loss and Th2 and Th17 bias are associated with the severity of severe fever with thrombocytopenia syndrome (SFTS)

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease caused by a novel bunyavirus with high mortality. Immune suppression is thought to be crucial in disease progression. However, data on immune responses during SFTS are scarce. This study aimed to evaluate the changes in CD4 T-cell subsets throughout the entirety of infection and analyse their relationships with disease severity in SFTS patients. In parallel with CD4 T-cell depletion, decreased Th1, Th2 and Treg numbers, but comparable Th17-cell numbers, were observed in deceased patients compared with those in surviving patients. Additionally, increased Th2 and Th17-cell percentages in the residual CD4 T-cell population led to aberrant Th2/Th1 and Th17/Treg ratios, which were positively correlated with disease severity. Collectively, our data indicated that CD4 T-cell deficiency, Th2 and Th17 bias were closely correlated with the severity of SFTS, indicating therapeutic potential of early immune interventions to ameliorate disease severity.

Abstract 4940: Nonredundant roles for immune checkpoint blockade and agonistic CD40 in mediating T-cell responses in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDA) is a highly aggressive cancer that is resistant to most treatments, with a five-year survival rate of ~10%. Immune checkpoint blockade (ICB) has had dramatic effects in many tumor histologies, but is ineffective in PDA. CD40 lies upstream of the immune checkpoints in the T-cell activation pathway, presenting a unique opportunity to intercede with T-cell activation independently of ICB. We hypothesized that administering agonistic CD40 antibody would prime effector T-cell populations, synergizing with ICB to provide therapeutic benefit in PDA. We administered agonistic CD40 monoclonal antibody (clone FGK45, anti-CD40) combined with anti-PD1 and anti-CTLA4 monoclonal antibodies (ICB) to mice bearing subcutaneous PDA tumors established using syngeneic tumor cell lines derived from the KrasG12D+/-;Trp53R172H+/-;Pdx-1 Cre (KPC) genetically engineered mouse model of PDA. While tumor regressions were rare in mice treated with ICB or anti-CD40 alone (1/7 mice in each group), 100% of mice treated with ICB + anti-CD40 experienced tumor regressions (7/7 mice). Cell depletion experiments showed early tumor regressions depended primarily on CD4 T cells, although both CD4 and CD8 T cells were required for long-term remission. 50% of mice (4/8) treated with ICB + anti-CD40 remained tumor-free (median survival 112 days) and 3/4 mice resisted tumor rechallenge, indicative of a long-lived memory T-cell response against PDA. Treatment with ICB + anti-CD40, but neither alone, increased the total intratumoral CD3+ T-cell population 3.8-fold (p&amp;lt;0.01), with increases in both the CD4+ and CD8+ T-cell compartments (6.7-fold and 3.3-fold, respectively, p &amp;lt;0.016). CD40 stimulation, but not ICB, modulated the CD4 compartment in the TME, increasing the proportion of CD43+CD11a+ antigen-specific CD4 T helpers (41 - 43% v. 10%, +/-ICB v. control, p &amp;lt;0.03) and reducing FoxP3+ CD4+ T regulatory cells (Tregs) 2.7 to 3.7-fold (+/- ICB, p &amp;lt; 0.0001). This resulted in an increased ratio of CD8 T effector cells to Tregs (7.5 to 10.7 CD8/Treg, anti-CD40 +/-ICB, p&amp;lt;0.01) specifically after treatment with anti-CD40, regardless of ICB addition. ICB alone increased the proportion of proliferating CD8 T cells in the tumor draining lymph node that were ‘"reinvigorated" Eomes+Tbet-Ki67+ (17-19% +/- CD40 v. 8% control, p &amp;lt;0.01), but was unable to increase the same CD8 T-cell population in the tumor. However, the addition of CD40 to ICB reduced the frequency of PD1+ CD8 T effectors in the tumor (25% v. 52% control, p &amp;lt; 0.05), suggesting a tumor-specific benefit of ICB on the exhausted T-cell compartment. These studies reveal the nonredundant roles that agonistic CD40 and ICB play in generating a robust T-cell response against PDA, and highlight the clinical potential of combining CD40 activation with ICB as a novel therapeutic approach in ICB-resistant tumors. Citation Format: Alexander H. Morrison, Katelyn T. Byrne, Robert H. Vonderheide. Nonredundant roles for immune checkpoint blockade and agonistic CD40 in mediating T-cell responses in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4940.

Preliminary biomarker and pharmacodynamic data from a phase I study of single-agent bispecific antibody T-cell engager GBR 1302 in subjects with HER2-positive cancers.

69 Background: HER2 is overexpressed in many solid tumors and is a validated therapeutic target. GBR 1302 is a HER2xCD3 bispecific antibody engineered (using Glenmark’s BEAT® platform) to direct T-cells to HER2-expressing tumor cells. GBR1302-101 (NCT02829372) is an ongoing, multicenter, open-label, first-in-human study of GBR 1302 in subjects with HER2-positive cancers to evaluate the safety, tolerability, and preliminary efficacy of GBR 1302, and to elucidate the mechanism(s) by which it redirects T-cells to tumor and enhances cytolytic activity of cytotoxic T-cells. Methods: Adults with progressive HER2-positive solid tumors with no available standard or curative treatment receive intravenous GBR 1302 on Day 1 and Day 15 in 28-day treatment cycles at escalating dose levels, starting at 1 ng/kg. The first 4 cohorts consist of a single subject; subsequent cohorts enroll using a 3+3 design. The primary and secondary efficacy and safety endpoints of this trial will be reported at the end of the study. Preliminary pharmacodynamic (PD) data are reported for cellular biomarkers and cytokines as assessed by FACS and ELISA in peripheral blood. Results: Beginning at 30 ng/kg dosing of GBR 1302 (Cohort 4), numbers of peripheral blood CD3, CD4, and CD8 positive T-cell populations decreased within 6 hours of initiating administration, but recovered to levels at or above baseline by 48 hours. A parallel, transient increase was observed in peripheral blood cytokines (IL-2, IL-6, IL-10, IFN-γ, TNF-α). At doses greater than 30 ng/kg, more pronounced cytokine increases were observed, which normalized at 12 hours. At the highest dose level for which data are available (n = 8 subjects; Cohort 5), changes from baseline in cytokine expression at ~340 hours were greater by ~60-fold for IL-6, ~30-fold for IL-2, ~3-fold for IFN-γ, ~5-fold for TNF-α, and ~18-fold for IL-10. Two subjects treated at 100 ng/kg experienced Grade 1 cytokine release syndrome, evidenced by short-lived fever spikes. Dose escalation is ongoing. Conclusions: Preliminary PD data indicate changes in peripheral T-cell populations and inflammatory cytokines following GBR 1302 treatment. Clinical trial information: NCT02829372.

Blood CXCR3+ CD4 T Cells Are Enriched in Inducible Replication Competent HIV in Aviremic Antiretroviral Therapy-Treated Individuals

We recently demonstrated that lymph nodes (LNs) PD-1+/T follicular helper (Tfh) cells from antiretroviral therapy (ART)-treated HIV-infected individuals were enriched in cells containing replication competent virus. However, the distribution of cells containing inducible replication competent virus has been only partially elucidated in blood memory CD4 T-cell populations including the Tfh cell counterpart circulating in blood (cTfh). In this context, we have investigated the distribution of (1) total HIV-infected cells and (2) cells containing replication competent and infectious virus within various blood and LN memory CD4 T-cell populations of conventional antiretroviral therapy (cART)-treated HIV-infected individuals. In the present study, we show that blood CXCR3-expressing memory CD4 T cells are enriched in cells containing inducible replication competent virus and contributed the most to the total pool of cells containing replication competent and infectious virus in blood. Interestingly, subsequent proviral sequence analysis did not indicate virus compartmentalization between blood and LN CD4 T-cell populations, suggesting dynamic interchanges between the two compartments. We then investigated whether the composition of blood HIV reservoir may reflect the polarization of LN CD4 T cells at the time of reservoir seeding and showed that LN PD-1+ CD4 T cells of viremic untreated HIV-infected individuals expressed significantly higher levels of CXCR3 as compared to CCR4 and/or CCR6, suggesting that blood CXCR3-expressing CD4 T cells may originate from LN PD-1+ CD4 T cells. Taken together, these results indicate that blood CXCR3-expressing CD4 T cells represent the major blood compartment containing inducible replication competent virus in treated aviremic HIV-infected individuals.

HIV and Age Do Not Synergistically Affect Age-Related T-Cell Markers.

Despite major progress in controlling HIV disease through antiretroviral therapy, changes in immune phenotype and function persist in individuals with chronic HIV, raising questions about accelerated aging of the immune system. We conducted a cross-sectional study (2005-2007) of HIV-infected (n = 111) and uninfected (n = 114) men from the Veterans Aging Cohort Study. All HIV-infected subjects were on antiretroviral therapy with VL <400 copies/mL for at least 3 years. T-cell markers were examined using flow cytometry. We evaluated the impact of HIV serostatus and age on T-cell phenotypes (expressed as percentages of the total CD4 and CD8 T-cell population) using multivariate linear regression, adjusted for smoking, alcohol, and race/ethnicity. We tested for interactions between HIV and age by including interaction terms. Among both HIV-infected and uninfected subjects, increasing age was associated with a decreased proportion of naive CD4 T cells (P = 0.014) and CD8 T cells (P < 0.0001). Both HIV infection and increasing age were associated with higher proportions of effector memory CD4 T cells (P < 0.0001 for HIV; P = 0.04 for age) and CD8 T cells (P = 0.0001 for HIV; P = 0.0004 for age). HIV infection, but not age, was associated with a higher proportion of activated CD8 T cells (P < 0.0001). For all T-cell subsets tested, there were no significant interactions between HIV infection and age. Age and HIV status independently altered the immune system, but we found no conclusive evidence that HIV infection and advancing age synergistically result in accelerated changes in age-associated T-cell markers among virally suppressed individuals.

In-vitro blockade of the CD4 receptor co-signal in antigen-specific T-cell stimulation cultures induces the outgrowth of potent CD4 independent T-cell effectors

T-cell receptor (TCR) redirected T cells are promising tools for adoptive cancer immunotherapy. Since not only CD8 but also CD4 T cells are key players for efficient antitumor responses, the targeted redirection of both subsets with the same antigen-specific TCR comes more and more into focus. Although rapidly evolving technologies enable the reliable genetic re-programming of T cells, the limited availability of TCRs that induce T-cell activation in both T-cell subsets without CD4/CD8 co-receptor contribution hampers the broad application of this approach. We developed a novel stimulation approach, which drives the activation and proliferation of CD4 T-cell populations capable of inducing effector functions in a CD4-independent manner. Naive-enriched CD4 T cells were stimulated against dendritic cells (DC) expressing allogeneic HLA-DP antigens upon RNA transfection and CD4/HLA interactions were blocked by the addition of CD4 binding antibody. Evolving CD4 T-cell populations were specifically activated independent of the CD4 co-signal and induced strong TCR-mediated IFN-γ secretion as well as cytolysis upon recognition of leukemia cells expressing HLA-DP antigen. Our novel stimulation approach may facilitate the generation of CD4 T cells as source for co-receptor independent TCRs for future immunotherapies.

T follicular regulatory cells in mice and men.

It has long been known that CD4 T cells are necessary to provide help to B cells, triggering a germinal centre (GC) reaction where affinity maturation and isotype switching occur. However, the nature of the dedicated CD4 helper T cells, known as T follicular helper (Tfh), was only recently described. Here, we review the biology and function of the recently described T follicular regulatory (Tfr) cells, another CD4 T-cell population also found within GCs but with regulatory function and characteristics. Tfr cells have been identified in mice and humans as simultaneously presenting characteristics of T follicular cells (namely CXCR5 expression) and regulatory T cells (including Foxp3 expression). These Tfr cells have been implicated in the regulation of the magnitude of the GC reaction, as well as in protection from immune-mediated pathology.

Aging-related changes in human T-cell repertoire over 20 years delineated by deep sequencing of peripheral T-cell receptors

Recent deep sequencing studies on T-cell receptor (TCR) repertoire have provided robust data to characterize diversity of T-cell immune responsiveness to a wide variety of peptide antigens, including viral and tumor antigens. The human TCR repertoire declines with age, but this decline has not been fully investigated longitudinally in individuals. Using a deep sequencing approach, we analyzed TCRβ repertoires longitudinally over approximately 20years, with ages ranging from 23 to 50years at the start (23 to 65years overall), in peripheral-blood CD4 and CD8 T-cell populations that were collected and cryopreserved 3 times at intervals of approximately 10years from each of 6 healthy adults (3 men and 3 women). Sequence data at the hypervariable complementarity determining region 3 (CDR3) in the TCRB gene locus were evaluated by applying a random-coefficient statistical regression model. Two outcomes were analyzed: total number of distinct TCRB CDR3 sequences as a TCR diversity metric, and clonality of the T-cell populations. TCR repertoire diversity decreased (p<0.001) and frequencies of clonal populations increased (p=0.003) with age in CD8 T cells, whereas CD4 T cells retained fairly diverse TCR repertoires along with relatively low clonality. We also found that approximately 10–30% and 30–80% of read sequences in CD4 and CD8 T cells, respectively, overlapped at different ages within each individual, indicating long-term stable maintenance of T-cell clonal composition. Moreover, many of the most frequent TCRB CDR3 sequences (i.e., top T-cell clones) persisted over 20years, and some of them expanded and exerted a dominating influence on clonality of peripheral T-cell populations. It is thus possible that persistence or expansion of top T-cell clones is a driver of T-cell immunity aging, and therefore represents a potential interventional target.

Phosphorylation of Y248 in the ITSM of PD-1 is indicative of PD-1-mediated inhibitory function

Abstract PD-1 is an inhibitory receptor expressed on activated T-cells. SHP-2 tyrosine phosphatase interacts with PD-1 and is critical for PD-1-mediated inhibition. The cytoplasmic tail of PD-1 contains an immunoreceptor tyrosine based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM). It has been reported that SHP-2 may interact with either ITIM or ITSM of PD-1. We sought to identify the precise motif of PD-1 that is mandatory for SHP-2 interaction and PD-1 inhibitory function. Using GST-SHP-2 fusion protein we determined that PD-1 interacted with SHP-2 after PD-1 ligation with simultaneous TCR/CD3-mediated activation. This interaction required phosphorylation of the ITSM and was abrogated when the ITSM tyrosine Y248 was mutated to phenylalanine. In contrast, when the ITIM tyrosine Y223 was mutated, interaction of PD-1 with SHP-2 remained unaffected. Based on these findings, we hypothesized that phosphorylation of Y248 might be indicative of PD-1-mediated inhibitory signaling. We generated an antibody specific for Y248 and examined expression and function of PD-1pY248+ T cells in peripheral blood from healthy humans. PD-1pY248+ cells were detected within the CD4 but mostly CD8T cell populations, mainly in central memory and effector memory subsets and in much lower extent in terminally differentiated effectors. Although PD-1high did not correlate with altered ability of CD8 T cells to produce effector cytokines, PD-1pY248+ expression correlated with impaired production of IFN-g and TNFa in response to TCR/CD3+CD28-mediated stimulation. Thus, PD-1pY248 might serve as a biomarker indicative of PD-1 mediated inhibitory signaling in patients with chronic infections and cancer.

Sirolimus, Post–Transplant Cyclophosphamide, and CTLA4-Ig Maintain Stable Mixed Chimerism In a Mismatched Murine Model

Abstract Hematopoietic stem cell transplantation (HSCT) is the only curative option for patients with sickle cell disease (SCD). We sought to extend our haploidentical HSCT regimen with nonmyeloablative conditioning. The objective of our study was to assess the ability of the immunosuppressive agent CTLA4-Ig to induce mixed chimerism in the haploidentical HSCT setting when combined with sirolimus, post-transplant cyclophosphamide (PT-Cy), or both. We used a mismatched mouse model with BALB/c donors and C57BL/6 recipients. Recipient mice received 200 cGy TBI on day of the transplant and were conditioned with or without sirolimus, PT-Cy, and/or CTLA4-Ig. Our data show that when CTLA4-Ig alone or CTLA4-Ig/PT-Cy are given, donor cells are not detected. However, mixed chimerism is maintained in mice who received either sirolimus/PT-Cy or sirolimus/PT-Cy given together with CTLA4-Ig over 60 days. Additionally our data indicate a significant increase in recovery of donor cells within CD8 T-cell, CD19 B-cell, and CD11b myeloid cell populations in groups conditioned with sirolimus/PT-Cy, or sirolimus/PT-Cy/CTLA4-Ig as compared to groups conditioned with CTLA4-Ig (p=0.003; p=0.002; p=0.049) alone or CTLA4-Ig/PT-Cy (p=0.001; p&amp;lt;0.0001; p=0.001) at 30 days, respectively. These data demonstrate that sirolimus in combination with PT-Cy and CTLA4-Ig is synergistic in an MHC-mismatched mouse model. The novel tri-drug group establishes mixed chimerism while conditioning with CTLA4-Ig alone or CTLA4-Ig/PT-Cy does not. The data also identify induction of stable mixed chimerism in specific cellular subpopulations within the sirolimus/PT-Cy and sirolimus/PT-Cy/CTLA4-Ig groups, indicating that these cells may play an important role in HCST.

Increase of circulating α4β7+ conventional memory CD4 and regulatory T cells in patients with common variable immunodeficiency (CVID)

This study investigated whether circulating α4β7+ expressing T cells could serve as a potential marker for gastrointestinal (GI) disease activity in patients with CVID. The analysis of α4β7+ T cells in the peripheral blood of 36 patients and 22 healthy donors (HD) revealed increased percentages of α4β7+ conventional memory CD4 T cells and Tregs, but not among CD8 T-cell populations in patients with CVID compared to HD. No differences between patients with and without chronic or acute GI symptoms were observed. EUROClass smB− and 21lo patients, had higher percentages of α4β7+ memory CD4 T cells compared to HD and smB+ or 21norm patients, respectively. In summary, the detection of α4β7+ T cells in the peripheral blood did not correlate with active or chronic gastrointestinal disease. The increase of these cells in smB− and 21lo patients adds another piece to the immune dysregulation observed in these patients.

Therapeutic Efficacy of 4-1BB Costimulation Is Abrogated by PD-1 Blockade in a Model of Spontaneous B-cell Lymphoma.

Combinations of mAbs that target various components of T-cell activation/inhibition may work synergistically to improve antitumor immunity against cancer. In this study, we investigated the therapeutic potential of combining an anticancer vaccination strategy with antibodies targeting an immune stimulatory (4-1BB) and immune inhibitory (PD-1) receptor, in a preclinical model of spontaneously arising c-Myc-driven B-cell lymphoma. In Eμ-myc transgenic mice, we reveal that 4-1BB agonistic mAb treatment alone was sufficient to drive antitumor immunity and prevent disease progression in 70% of mice. When combined with an α-GalCer-loaded, irradiated tumor cell vaccine, 4-1BB mAb treatment led to increased expansion of effector CD8 T-cell populations and protection of long-term surviving mice against tumor rechallenge. Unexpectedly, PD-1 blockade did not provide therapeutic benefit. The T-cell-promoting effects and antitumor activity of 4-1BB mAb were diminished when used simultaneously with a PD-1-blocking mAb. This was associated with a rapid and dramatic reduction in effector CD8+ T-cell subsets in the presence of PD-1 blockade. These findings reveal that supporting T-cell activation therapeutically is effective for controlling B-cell lymphomas; however, caution is required when combining antibody-mediated modulation of both costimulatory and coinhibitory T-cell receptors. Cancer Immunol Res; 5(3); 191-7. ©2017 AACR.

An altered endometrial CD8 tissue resident memory T cell population in recurrent miscarriage

When trying to conceive 1% of couples have recurrent miscarriages, defined as three or more consecutive pregnancy losses. This is not accounted for by the known incidence of chromosomal aneuploidy in miscarriage, and it has been suggested that there is an immunological aetiology. The endometrial mucosa is populated by a variety of immune cells which in addition to providing host pathogen immunity must facilitate pregnancy. Here we characterise the endometrial CD8-T cell population during the embryonic window of implantation and find that the majority of cells are tissue resident memory T cells with high levels of CD69 and CD103 expression, proteins that prevent cells egress. We demonstrate that unexplained recurrent miscarriage is associated with significantly decreased expression of the T-cell co-receptor CD8 and tissue residency marker CD69. These cells differ from those found in control women, with less expression of CD127 indicating a lack of homeostatic cell control through IL-7 signalling. Nevertheless this population is resident in the endometrium of women who have RM, more than three months after the last miscarriage, indicating that the memory CD8-T cell population is altered in RM patients. This is the first evidence of a differing pre-pregnancy phenotype in endometrial immune cells in RM.

Intrinsic 4-1BB signals are indispensable for the establishment of an influenza-specific tissue-resident memory CD8 T-cell population in the lung.

The induction of long-lived heterotypic T-cell protection against influenza virus remains elusive, despite the conservation of T-cell epitopes. T-cell protection against influenza is critically dependent on lung-resident memory T cells (Trm). Here we show that intranasal administration of 4-1BBL along with influenza nucleoprotein in a replication-defective adenovirus vector to influenza pre-immune mice induces a remarkably stable circulating effector memory CD8 T-cell population characterized by higher IL-7Rα expression than control-boosted T cells, as well as a substantial lung parenchymal CD69+ CD8 Trm population, including both CD103+ and CD103- cells. These T-cell responses persist to greater than 200 days post-boost and protect against lethal influenza challenge in aged (year old) mice. The expansion of the nucleoprotein-specific CD8 Trm population during boosting involves recruitment of circulating antigen-specific cells and is critically dependent on local rather than systemic administration of 4-1BBL as well as on 4-1BB on the CD8 T cells. Moreover, during primary influenza infection of mixed bone marrow chimeras, 4-1BB-deficient T cells fail to contribute to the lung-resident Trm population. These findings establish both endogenous and supraphysiological 4-1BBL as a critical regulator of lung-resident memory CD8 T cells during influenza infection.

Depletion of CD52-positive cells inhibits the development of central nervous system autoimmune disease, but deletes an immune-tolerance promoting CD8 T-cell population. Implications for secondary autoimmunity of alemtuzumab in multiple sclerosis.

SummaryThe objective was to determine whether CD52 lymphocyte depletion can act to promote immunological tolerance induction by way of intravenous antigen administration such that it could be used to either improve efficiency of multiple sclerosis (MS) inhibition or inhibit secondary autoimmunities that may occur following alemtuzumab use in MS. Relapsing experimental autoimmune encephalomyelitis was induced in ABH mice and immune cell depletion was therapeutically applied using mouse CD52 or CD4 (in conjunction with CD8 or CD20) depleting monoclonal antibodies. Immunological unresponsiveness was then subsequently induced using intravenous central nervous system antigens and responses were assessed clinically. A dose–response of CD4 monoclonal antibody depletion indicated that the 60–70% functional CD4 T‐cell depletion achieved in perceived failed trials in MS was perhaps too low to even stop disease in animals. However, more marked (~75–90%) physical depletion of CD4 T cells by CD4 and CD52 depleting antibodies inhibited relapsing disease. Surprisingly, in contrast to CD4 depletion, CD52 depletion blocked robust immunological unresponsiveness through a mechanism involving CD8 T cells. Although efficacy was related to the level of CD4 T‐cell depletion, the observations that CD52 depletion of CD19 B cells was less marked in lymphoid organs than in the blood provides a rationale for the rapid B‐cell hyper‐repopulation that occurs following alemtuzumab administration in MS. That B cells repopulate in the relative absence of T‐cell regulatory mechanisms that promote immune tolerance may account for the secondary B‐cell autoimmunities, which occur following alemtuzumab treatment of MS.

Systemic Immunity Is Required for Effective Cancer Immunotherapy

Immune responses involve coordination across cell types and tissues. However, studies in cancer immunotherapy have focused heavily on local immune responses in the tumor microenvironment. To investigate immune activity more broadly, we performed an organism-wide study in genetically engineered cancer models using mass cytometry. We analyzed immune responses in several tissues after immunotherapy by developing intuitive models for visualizing single-cell data with statistical inference. Immune activation was evident in the tumor and systemically shortly after effective therapy was administered. However, during tumor rejection, only peripheral immune cells sustained their proliferation. This systemic response was coordinated across tissues and required for tumor eradication in several immunotherapy models. An emergent population of peripheral CD4 Tcells conferred protection against new tumors and was significantly expanded in patients responding to immunotherapy. These studies demonstrate the critical impact of systemic immune responses that drive tumor rejection.