Asplenic Individuals Research Articles

Refractory autoimmune hemolytic anemia secondary to Babesia

Introduction: Babesia is endemic in the northeast and upper midwestern United States. Two species that cause human infections are Babesia microti and Babesia divergens. The parasite is transmitted by the bite of the tick Ixodes scapularis. Another mode of transmission is blood transfusion producing either an asymptomatic to mild flu-like illness or hemolytic anemia in immunocompromised and asplenic individuals. Hemolysis is usually non-immune and attributed to lysis of infected erythrocytes. Rarely the infection may cause immune dysregulation and lead to the formation of autoantibodies that cause immune mediated hemolytic anemia. Case Report: A previously healthy young adult male with a recent history of multiple blood transfusions, presented with refractory autoimmune hemolytic anemia within two months of transfusion. The anemia was unresponsive to various immunosuppressive medications and blood transfusions. On follow-up, his peripheral smears showed heavy parasitemia consistent with Babesia species. The organism was speciated to Babesia microti by polymerase chain reaction at the Center for Disease Control. The patient was treated with intravenous quinidine and oral clindamycin. Immune hemolytic anemia resolved following the treatment of Babesiosis. Conclusion: In conclusion, Babesiosis should be in the differential diagnosis of autoimmune hemolytic anemia in a patient with a history of blood transfusion and poor response to steroids or immunosuppressive drugs.

Congenital Asplenia Interrupts Immune Homeostasis and Leads to Excessive Systemic Inflammation in Zebrafish.

Splenectomy or congenital asplenia in humans increases susceptibility to infections. We have previously reported that congenital asplenia in zebrafish reduces resistance to Aeromonas hydrophila infection. However, the molecular mechanism of systemic immune response in congenitally asplenic individuals is largely unexplored. In this study, we found that pro-inflammatory cytokines were more highly induced in congenitally asplenic zebrafish than wild-type after pathogenic A. hydrophila infection and lipopolysaccharide exposure. In addition, a higher aggregation of apoptotic cells was observed in congenitally asplenic zebrafish than that in wild-type. Next, we examined the transcriptome profiles of whole kidneys from wild-type and congenitally asplenic zebrafish to investigate the effects of congenital asplenia on innate and adaptive immune responses induced by the inactivated A. hydrophila. Congenital asplenia inactivated the splenic anti-inflammatory reflex, disrupted immune homeostasis, and induced excessive inflammation as evidenced by the highly induced stress response–related biological processes, inflammatory and apoptosis-associated pathways, and pro-inflammatory cytokines/chemokines in congenitally asplenic zebrafish compared with wild-type after vaccination. In addition, complement component genes (c3a.1, c3a.6, c4, c6, and c9) and several important immune-related genes (tabp.1, tap1, hamp, prg4b, nfil3, defbl1, psmb9a, tfr1a, and sae1) were downregulated in congenitally asplenic zebrafish. Furthermore, congenital asplenia impaired adaptive immunity as demonstrated by downregulation of biological processes and signaling pathways involved in adaptive immune response after vaccination in congenitally asplenic zebrafish. The expression of MHCII/IgM was also significantly reduced in the congenitally asplenic zebrafish when compared with wild-type. Together, our study provides an in-depth understanding of spleen function in controlling immune homeostasis and may offer insight into the pathological response in splenectomized or congenitally asplenic patients after infections.

Pre-clinical evaluation of a whole-parasite vaccine to control human babesiosis

Babesia spp. are tick-transmitted intra-erythrocytic protozoan parasites that infect humans and animals, causing a flu-like illness and hemolytic anemia. There is currently no human vaccine available. People most at risk of severe disease are the elderly, immunosuppressed, and asplenic individuals. B.microti and B.divergens are the predominant species affecting humans. Here, we present a whole-parasite Babesia vaccine. To establish proof-of-principle, we employed chemically attenuated B.microti parasitized red blood cells from infected mice. To aid clinical translation, we produced liposomes containing killed parasite material. Vaccination significantly reduces peak parasitemia following challenge. B cells and anti-parasite antibodies do not significantly contribute to vaccine efficacy. Protection is abrogated by the removal of CD4+ Tcells or macrophages prior to challenge. Importantly, splenectomized mice are protected by vaccination. To further facilitate translation, we prepared a culture-based liposomal vaccine and demonstrate that this performs as a universal vaccine inducing immunity against different human Babesia species.

Novel Targeting to XCR1+ Dendritic Cells Using Allogeneic T Cells for Polytopical Antibody Responses in the Lymph Nodes.

Vaccination strategy that induce efficient antibody responses polytopically in most lymph nodes (LNs) against infections has not been established yet. Because donor-specific blood transfusion induces anti-donor class I MHC antibody production in splenectomized rats, we examined the mechanism and significance of this response. Among the donor blood components, T cells were the most efficient immunogens, inducing recipient T cell and B cell proliferative responses not only in the spleen, but also in the peripheral and gut LNs. Donor T cells soon migrated to the splenic T cell area and the LNs, with a temporary significant increase in recipient NK cells. XCR1+ resident dendritic cells (DCs), but not XCR1− DCs, selectively phagocytosed donor class I MHC+ fragments after 1 day. After 1.5 days, both DC subsets formed clusters with recipient CD4+ T cells, which proliferated within these clusters. Inhibition of donor T cell migration or depletion of NK cells by pretreatment with pertussis toxin or anti-asialoGM1 antibody, respectively, significantly suppressed DC phagocytosis and subsequent immune responses. Three allogeneic strains with different NK activities had the same response but with different intensity. Donor T cell proliferation was not required, indicating that the graft vs. host reaction is dispensable. Intravenous transfer of antigen-labeled and mitotic inhibitor-treated allogeneic, but not syngeneic, T cells induced a polytopical antibody response to labeled antigens in the LNs of splenectomized rats. These results demonstrate a novel mechanism of alloresponses polytopically in the secondary lymphoid organs (SLOs) induced by allogeneic T cells. Donor T cells behave as self-migratory antigen ferries to be delivered to resident XCR1+ DCs with negligible commitment of migratory DCs. Allogeneic T cells may be clinically applicable as vaccine vectors for polytopical prophylactic antibody production even in asplenic or hyposplenic individuals.

The effect of splenectomy on the levels of PCV-13-induced memory B- and T cells.

Splenectomised patients are associated with lifelong risk of fatal overwhelming post-splenectomy infection (OPSI), which is mostly caused by Streptococcus pneumoniae. Today OPSI cases can still be reported even in patients with appropriate vaccination. In our study, the levels of vaccine-specific memory B- and T cells were compared between control and splenectomised patients to enlighten the underlying reason. Five healthy and 14 post-traumatic splenectomised individuals were vaccinated with 13-valent pneumococcal conjugate vaccine (PCV-13) followed by 23-valent pneumococcal polysaccharide vaccine (PPV-23). The levels of memory B- and T cells were compared by ELISPOT analysis. Splenectomised patients generated reduced levels of memory IgG B cells in response to PCV-13 vaccination, while the memory IFN-γ T-cell levels were undetectable in asplenic patients. This was despite the detection of vaccine-induced memory T-cell levels in control patients, which were analysed simultaneously following the same experimental protocol. Our results suggest that spleen is important, but not essential, for survival and/or generation of memory IgG B cells. In contrast, it seems to be indispensable for PCV-13-specific memory TH 1-cell levels. Studies enhancing the levels of vaccine-induced memory cells and further enlightening the immune responses in asplenic individuals are required to develop more effective vaccination strategies against OPSI.

Infection related late mortality in survivors of childhood cancer with asplenia or radiation-induced hyposplenism: A report from the Childhood Cancer Survivor Study.

10563 Background: Asplenia or hyposplenism can develop in survivors of childhood cancer following splenectomy or radiotherapy exposure to the left upper quadrant of the abdomen (LUQ). Knowledge regarding long-term infection related outcomes for these survivors is limited. Methods: Infection related late mortality (sepsis, meningitis or pneumonia) was evaluated in 20,805 5-year survivors (diagnosed <21 years of age from 1970-1999, median follow-up 26 years, range 5-44) using cumulative incidence and Poisson regression models to calculate adjusted relative risk (RR) and 95% confidence intervals (CI). Average LUQ radiation was calculated as a surrogate for splenic radiation. Results: Treatment included splenectomy for 1328 survivors (6%). An additional 10,295 (49%) were exposed to LUQ radiotherapy without splenectomy. The cumulative incidence of infection related late mortality was 1.4% (95%CI: 0.7%-2.2%) at 35 years after splenectomy and 0.6% (95%CI: 0.4%-0.8%) after LUQ radiotherapy, with a total of 78 deaths attributable to infectious causes (25 sepsis, 1 meningitis, 52 pneumonia). Splenectomy (RR=8.4, p<0.001) and increasing LUQ radiotherapy dose (p<0.001) were independently associated with infection related late mortality (Table). Conclusions: Splenectomy and LUQ radiotherapy increased risk for infection related late mortality. While infectious mortality increased with increasing LUQ radiation dose, even lower dose exposure (<10Gy) increased risk substantially. Accordingly, cancer survivors exposed to LUQ radiotherapy should be considered at risk for functional asplenia and managed similarly to asplenic individuals with respect to vaccinations and febrile illnesses. [Table: see text]

Anti-Pneumococcal Vaccine-Induced Cellular Immune Responses in Post-Traumatic Splenectomized Individuals.

Splenectomy is associated with increased risk of overwhelming post-splenectomy infections despite proper anti-pneumococcal vaccination. As most studies concentrated on vaccination-induced humoral immunity, the cellular immune responses triggered in splenectomized patients are not yet well studied. The present study aims to investigate this area as it can contribute to the development of more effective vaccination strategies. Five healthy and 14 splenectomized patients were vaccinated with pneumococcal conjugate polysaccharide vaccine (PCV) followed by pneumococcal polysaccharide vaccine according to the guidelines established by Advisory Committee on Immunization Practices. PBMC samples collected 0, 8, and 12weeks after PCV immunization were in vitro stimulated with PCV. Levels of lymphoproliferation, TH cell differentiation, and cytokine release were assessed by carboxyfluorescein succinimidyl ester labeling, intracellular cytokine staining, and ELISA, respectively. While TH1-dominated immune response was detected in both groups, asplenic individuals generated significantly lower levels of TH1 cells following in vitro stimulation. Similarly, levels of IFN-γ, IL-4, and IL-17 release and lymphoproliferation were significantly lower in asplenic patients. According to our data, splenectomy negatively influences the levels of PCV-induced lymphoproliferation, TH1 differentiation, and cytokine release. Besides, PCV failed to induce TH17-dominant immune response which is crucial for protection against extracellular pathogens.

A global map of genetic diversity in Babesia microti reveals strong population structure and identifies variants associated with clinical relapse.

Human babesiosis caused by Babesia microti is an emerging tick-borne zoonosis of increasing importance due to its rising incidence and expanding geographic range(1). Infection with this organism, an intraerythrocytic parasite of the phylum Apicomplexa, causes a febrile syndrome similar to malaria(2). Relapsing disease is common among immunocompromised and asplenic individuals(3,4) and drug resistance has recently been reported(5). To investigate the origin and genetic diversity of this parasite, we sequenced the complete genomes of 42 B. microti samples from around the world, including deep coverage of clinical infections at endemic sites in the continental USA. Samples from the continental USA segregate into a Northeast lineage and a Midwest lineage, with subsequent divergence of subpopulations along geographic lines. We identify parasite variants that associate with relapsing disease, including amino acid substitutions in the atovaquone-binding regions of cytochrome b (cytb) and the azithromycin-binding region of ribosomal protein subunit L4 (rpl4). Our results shed light on the origin, diversity and evolution of B. microti, suggest possible mechanisms for clinical relapse, and create the foundation for further research on this emerging pathogen.

Vaccinations in asplenic adults.

The recommended immunizations for adult asplenic patients are reviewed. Patients without a spleen are at risk of developing overwhelming postsplenectomy infections due to encapsulated organisms, mainly pneumococcal, meningococcal, and Haemophilus influenzae type b (Hib). Due to the high mortality rates associated with these infections, vaccinations are recommended as a preventive measure. It is challenging to ensure optimal immunizations in these high-risk patients due to the number of recommended vaccines, the availability of multiple formulations, and the inability to administer specific formulations at the same time, as well as differences in subsequent vaccine administration schedules. Pharmacists play a key role in recommending specific vaccines and timing for these patients in order to achieve the most robust immune response. This article reviews the specific recommendations for pneumococcal, meningococcal, Hib, and influenza vaccinations in asplenic patients. In order to prevent potentially life-threatening infections, asplenic individuals should be vaccinated against S. pneumoniae, N. meningitidis, Hib, and influenza. The optimal timing of vaccination in relation to splenectomy depends on the nature of the splenectomy.

A review of guidance on immunization in persons with defective or deficient splenic function.

The spleen acts as a blood filter and lymphopoietic organ. Asplenic and hyposplenic individuals are more susceptible to serious infections caused by encapsulated bacteria but they can be protected by antibiotic prophylaxis and immunizations. Recent progress in vaccinology means prophylaxis is now successful in the vast majority of serious infections with pneumococci, meningococci and Haemophilus influenzae type b responsible for the majority of cases of overwhelming sepsis in asplenic patients. Current guidelines are coherent. Physicians treating patients with conditions associated with hyposplenism are ethically obliged to immunize their patients using the vaccines currently available to protect them from largely preventable, life-threatening infections.

Investigation of the protective effects of beta-D-glucan against invasive encapsulated Streptococcus pneumoniae sepsis in splenectomized rats

In asplenic individuals depending on the weakness of the immune response, sepsis are known to be developed with a high mortality rate. The most common species which are responsible for sepsis are encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis. Sepsis caused by immune deficiencies linked to splenectomy leads to infections particularly in the lungs and liver and causes multiple organ failure. On the other hand, -D-glucan (BDG), a branched glucose polymer, shows immunomodulatory activity, by enhancing the resistance of the host against microbial agents, and promotes phagocytic and proliferative activities of reticuloendothelial system. The aim of this experimental study was to investigate the effects of BDG alone and in combination with ceftriaxone on sepsis caused by encapsulated invasive S.pneumoniae serotype 19F. A total of 36 Sprague-Dawley rats were used in the study, and the animals (6 in each group) were equally divided into six groups as control, splenectomy, sepsis, BDG, ceftriaxone and BDG+ceftriaxone groups. Treatment groups were intravenously infected with S.pneumoniae 19F strain, and after sacrification, microbiological [bacterial counts (cfu/mL)], biochemical (myeloperoxidase activity, DNA oxidation, specific IgM and IgG levels) and histopathological analysis were performed in the tissue samples. In the study, BDG, ceftriaxone and BDG+ceftriaxone groups had statistically significant decrease in the amount of bacteria in all tissues when compared to the sepsis group (p<0.05). We demonstrated that, BDG alone or combined treatment partially recovered the low serum IgM levels in splenectomized rats (p<0.001 ve p<0.02, respectively) and completely inhibited oxidative DNA damage in lung and liver after S.pneumoniae infection (p<0.00001). In addition, BDG alone or combined treatment fairly minimized the presence of bacteria in all tissues, when compared with sepsis group (p<0.00001). The data of our study suggests that, BDG, an immunomodulatory agent, alone and in combination with ceftriaxone can reverse the systemic inflammatory reaction in S.pneumoniae sepsis and thereby can reduce multiple organ failure.

Vaccination status and immune response to 13-valent pneumococcal conjugate vaccine in asplenic individuals

Overwhelming post-splenectomy infection (OPSI) is immediately life-threatening and vaccination against encapsulated bacteria, in particular pneumococci, decreases its incidence.First, we investigated the adherence to vaccination guidelines in a retrospective study of the hospital records of splenectomised patients. Second, patients were asked to complete a questionnaire and invited to participate in a study where 12-valent pneumococcal serotype-specific IgG concentrations were determined before and 4 to 6 weeks after vaccination with PCV13.Of 79 individuals who underwent splenectomy between 2000 and 2012: 81.0% received pneumococcal vaccine, 51.9% received vaccine against Haemophilus influenzae type B and 22.8% received meningococcal vaccine. 31 individuals were deceased. 33 individuals completed questionnaires and accepted participation in the second part of the study. The participants consisted of two groups: (1) prior PPV23 (n=24) and (2) prior PPV23+PCV13 (n=9). In group 1, pre-PCV13 GMC's≥0.35μg/mL were observed for serotypes 1, 4, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F, and GMC's<0.35μg/mL for serotypes 3 and 5, significant increases pre- to post-PCV13 were found for serotypes 1, 3, 4, 5, 7F, 18C, 19A, 23F (p≤0.001) and 19F (p=0.01) and all 12 serotypes-specific GMC were above 0.35μg/mL after vaccination. Group 2 did not receive vaccine in this study, but blood tests showed all 12 serotype-specific GMC>0.35μg/mL.Adherence to guidelines regarding primary pneumococcal vaccination was adequate but only a minority received the recommended meningococcal vaccination.High levels of pneumococcal serotype-specific antibodies were observed in the previous PPV23 vaccinated group, and more pronounced in the previous PCV13 group, and our data suggests that PCV13 is immunogenic for serotypes 1, 3, 4, 5, 7F, 18C, 19A, 19F and 23F, if used as a booster dose in asplenic patients with previous PPV23 vaccination.

Antigen-specific B-cell response to 13-valent pneumococcal conjugate vaccine in asplenic individuals with β-thalassemia previously immunized with 23-valent pneumococcal polysaccharide vaccine.

Current guidelines recommend a combined schedule of a 13-valent pneumococcal conjugate vaccine (PCV13) and PPSV23 (23-valent polysaccharide vaccine) for asplenic individuals. We show that PCV13 induces a T-dependent immune response in asplenic individuals with β-thalassemia, but previous PPSV23s affect the memory B-cell response in a dose- and time-dependent manner. Clinical Trials Registration. NCT01846923.

Preserved antibody levels and loss of memory B cells against pneumococcus and tetanus after splenectomy: Tailoring better vaccination strategies

Splenectomized patients are exposed to an increased risk of septicemia caused by encapsulated bacteria. Defense against infection is ensured by preformed serum antibodies produced by long-lived plasma cells and by memory B cells that secrete immunoglobulin in response to specific antigenic stimuli. Studying a group of asplenic individuals (57 adults and 21 children) without additional immunologic defects, we found that spleen removal does not alter serum anti-pneumococcal polysaccharide (PnPS) IgG concentration, but reduces the number of PnPS-specific memory B cells, of both IgM and IgG isotypes. The number of specific memory B cells was low in splenectomized adults and children that had received the PnPS vaccine either before or after splenectomy. Seven children were given the 13-valent pneumococcal conjugated vaccine after splenectomy. In this group, the number of PnPS-specific IgG memory B cells was similar to that of eusplenic children, suggesting that pneumococcal conjugated vaccine administered after splenectomy is able to restore the pool of anti-PnPS IgG memory B cells. Our data further elucidate the crucial role of the spleen in the immunological response to infections caused by encapsulated bacteria and suggest that glycoconjugated vaccines may be the most suitable choice to generate IgG-mediated protection in these patients.

The role of TLR2 in the host response to pneumococcal pneumonia in absence of the spleen

BackgroundAsplenic individuals are susceptible for overwhelming infection with Streptococcus pneumoniae, carrying a high mortality. Although Toll-like receptor (TLR)-2 is considered the major receptor for Gram-positive bacteria in innate immunity, it does not play a major role in host defense against pneumococcal pneumonia. We wanted to investigate if in absence of an intact spleen as a first line of defense, the role of TLR2 during pneumococcal pneumonia becomes more significant, thereby explaining its insignificant role during infections in immune competent hosts.MethodsWe intranasally infected splenectomized wildtype (WT), TLR2 knock-out (KO) and TLR2/4 double KO mice with either serotype 2 or 3 S. pneumoniae.ResultsThere were no differences between asplenic WT and TLR2KO mice of bacterial loads in lung homogenates and blood, cytokine and chemokine levels in the lungs, and lung pathology scores. TLR2/4 double KO mice were not impaired in bacterial control as well, which indicates that besides the interaction between S. pneumoniae and TLR2, the interaction between pneumolysin and TLR4 does not stimulate antibacterial defense in the asplenic host either.ConclusionsThese results argue against a significant role of TLR2 in host defense during S. pneumoniae pneumonia in the asplenic state. Therefore, other components can provide sufficient backup mechanisms for TLR2 deficiency in the defense against intrapulmonary infections with S. pneumoniae of the otherwise immune competent host.

Soluble BAFF Levels Inversely Correlate with Peripheral B Cell Numbers and the Expression of BAFF Receptors

The TNF family member protein BAFF/BLyS is essential for B cell survival and plays an important role in regulating class switch recombination as well as in the selection of autoreactive B cells. In humans, increased concentrations of soluble BAFF are found in different pathological conditions, which may be as diverse as autoimmune diseases, B cell malignancies, and primary Ab deficiencies (PAD). Because the mechanisms that regulate BAFF levels are not well understood, we newly developed a set of mAbs against human BAFF to study the parameters that determine the concentrations of soluble BAFF in circulation. Patients with PAD, including severe functional B cell defects such as BTK, BAFF-R, or TACI deficiency, were found to have higher BAFF levels than asplenic individuals, patients after anti-CD20 B cell depletion, chronic lymphocytic leukemia patients, or healthy donors. In a comparable manner, mice constitutively expressing human BAFF were found to have higher concentrations of BAFF in the absence than in the presence of B cells. Therefore, our data strongly suggest that BAFF steady-state concentrations mainly depend on the number of B cells as well as on the expression of BAFF-binding receptors. Because most patients with PAD have high levels of circulating BAFF, the increase in BAFF concentrations cannot compensate defects in B cell development and function.

Antibody response to Haemophilus influenzae type-b conjugate vaccine in children and young adults with congenital asplenia or after undergoing splenectomy

Absence of the spleen constitutes a risk of infection caused by encapsulated bacteria. The aim of our study was to determine the immune response to Haemophilus influenzae type-b (Hib) conjugate vaccine (HibCV) in asplenic individuals, considering the cause of asplenia, the age when splenectomy was carried out, and previous Hib vaccinations. Twenty asplenic patients, aged five to 25 years, were immunized with a single dose of HibCV. The specific antibody concentrations against HibCV were measured by enzyme-linked immunosorbent assay. Before vaccinations, the geometric mean antibody concentration (GMC) had an average value of 3.21 μg/ml and was comparable for all of the patients, regardless of the causes of asplenia. After vaccinations, the GMC was significantly higher, with an average of 6.78 μg/ml. Further, 4.5 years after vaccinations, the GMC was comparable to that of previously unvaccinated children. Moreover, 17/20 patients had GMC ≥ 1.0 μg/ml, which included all of the children with congenital asplenia, children splenectomized before the age of six years, and only 57% of children splenectomized after that age. HibCV gives asplenic patients long-term protection. Hence, HibCV should be administered regardless of previous vaccinations and time from splenectomy, even if antibody evaluation is not available.

Protecting asplenic individuals from fulminant pneumococcal disease

Rapid communications Case report: Fulminant pneumococcal sepsis in an unvaccinated asplenic patient in Italy 4 by M Chironna, A Sallustio, A De Robertis, M Quarto, C Germinario Syndromic surveillance to assess the potential public health impact of the Icelandic volcanic ash plume across the United Kingdom, April 2010 6 by AJ Elliot, N Singh, P Loveridge, S Harcourt, S Smith, R Pnaiser, K Kavanagh, C Robertson, CN Ramsay, J McMenamin, A Kibble, V Murray, S Ibbotson, M Catchpole, B McCloskey, GE Smith Upsurge of infections caused by Salmonella Concord among Ethiopian adoptees in Denmark, 2009 10 by R Sjogren Hendriksen, C Kjelso, M Torpdahl, S Ethelberg, K Molbak, FM Aarestrup

Use of rituximab for refractory cytopenias associated with autoimmune lymphoproliferative syndrome (ALPS).

ALPS is a disorder of apoptosis resulting in accumulation of autoreactive lymphocytes, leading to marked lymphadenopathy, hepatosplenomegaly, and multilineage cytopenias due to splenic sequestration and/or autoimmune destruction often presenting in childhood. We summarize our experience of rituximab use during the last 8 years in 12 patients, 9 children, and 3 adults, out of 259 individuals with ALPS, belonging to 166 families currently enrolled in studies at the National Institutes of Health. Refractory immune thrombocytopenia (platelet count <20,000) in nine patients and autoimmune hemolytic anemia (AIHA) in three patients led to treatment with rituximab. Among them, seven patients had undergone prior surgical splenectomy; three had significant splenomegaly; and two had no palpable spleen. In seven out of nine patients with ALPS and thrombocytopenia, rituximab therapy led to median response duration of 21 months (range 14-36 months). In contrast, none of the three children treated with rituximab for AIHA responded. Noted toxicities included profound and prolonged hypogammaglobulinemia in three patients requiring replacement IVIG, total absence of antibody response to polysaccharide vaccines lasting up to 4 years after rituximab infusions in one patient and prolonged neutropenia in one patient. Toxicities including hypogammaglobulinemia and neutropenia constitute an additional infection risk burden, especially in asplenic individuals, and may warrant avoidance of rituximab until other immunosuppressive medication options are exhausted. Long-term follow-up of ALPS patients with cytopenias after any treatment is necessary to determine relative risks and benefits.

Immune response to pneumococcal conjugate vaccination in asplenic individuals

Asplenic individuals are at increased risk of infection with Streptococcus pneumoniae. The immune response to pneumococcal conjugate vaccine has not been investigated in this clinical risk group. We investigated immune responses to pneumococcal vaccination in asplenic individuals. Eligible subjects aged ≥ 4 years received one dose 7-valent pneumococcal conjugate vaccine (PCV7) and, if no prior 23-valent polysaccharide vaccine (PPV23) had been received within previous 5 years, one dose was given 6 months following PCV7. Pre- and post-vaccination blood samples were taken. Pneumococcal serotype-specific IgG levels were determined for 9 serotypes; the 7 in PCV7 plus serotypes1 and by standardised ELISA. One hundred and eleven asplenic individuals were recruited (median age 54.8 years, (18.1-81.8)). Median age at splenectomy was 29.6 years (3.6-78.3); 108 (97.3%) individuals had previously received PPV23. Compliance with UK recommendations on immunization and prophylaxis in this group was poor, 91 (82%) subjects had received Haemophilus influenzae type b conjugate vaccine and only 68 (62%) had received meningococcal serogroup C conjugate vaccine. In total 61 (55%) subjects were taking antibiotic prophylaxis and 12 subjects had reported previous invasive pneumococcal disease, 5 episodes of which occurred post-splenectomy. High serotype-specific IgG concentrations were observed pre-PCV7, with significant increases (p