Graft-versus-host disease is the major determinant of humoral responses to the AS03-adjuvanted influenza A/09/H1N1 vaccine in allogeneic hematopoietic stem cell transplant recipients

Background

Responses to influenza vaccines are poorly characterized in immunocompromised patients. The goal of this study was to assess the efficacy of the AS03-adjuvanted influenza H1N1/A/09 vaccine in allogeneic hematopoietic stem cell transplant recipients.

Design and Methods

We enrolled 65 patients and 138 controls in an open prospective study. Controls received one dose and patients 2 doses of the AS03-adjuvanted influenza H1N1/A/09 vaccine at a 3-week interval. Geometric mean titers and seroprotection/seroconversion rates were determined by hemagglutination inhibition before and four weeks after the last immunization. Clinical and biological markers, including immunoglobulins, CD3⁺, CD4⁺, CD8⁺ and naïve CD4⁺ T-cell counts were assessed in all patients.

Results

Baseline seroprotection rates were low in patients (6.6%) and controls (14.8%). After 2 doses, patients (n=57, 92.3%) achieved similar seroprotection rates (84% vs. 87%, P=0.65) and antibody titers (305 vs. 340, P=0.88) as controls (n=131, 93.9%) after one dose. In univariate analysis, transplant-to-vaccination interval less than 12 months, active graft-versus-host disease, immunosuppressive drugs, hemoglobin less than 12g/L, lymphopenia less than1G/L, IgG less than 4g/L, IgA less than 0.5g/L, IgM less than 0.5g/L and naive CD4⁺ T cells less than 150/μL were significantly associated with weaker responses. Multivariate analysis identified transplant-to-vaccination interval and active graft-versus-host disease as the most powerful negative predictors of antibody responses (P=0.04 and P=0.002, respectively). Vaccination was well tolerated in both cohorts.

Conclusions

In allogeneic hematopoietic stem cell transplant recipients, 2 doses of an adjuvanted influenza vaccine elicited comparable responses to a single dose in healthy individuals. However, vaccine responses remained poor in patients with ongoing graft-versus-host disease, supporting the need for additional strategies in this high-risk patient population. (ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT01022905","term_id":"NCT01022905"}}NCT01022905)     

Tumor-specific allogeneic cells for cancer therapy

Adoptive cell transfer (ACT) therapy involves transfer of therapeutic lymphocytes to patients mostly for the treatment of cancer and viral infections. One modality to generate therapeutic lymphocytes is to genetically engineer them to express a chimeric antigen receptor (CAR) capable of recognizing the desired target. Current ACT approaches employ the patient's own (syngeneic) lymphocytes, which is both economically and technically challenging. Using foreign (allogeneic) lymphocytes in ACT is problematic because of the severe immunological reaction that occurs between genetically mismatched individuals. However, recently our group has developed a protocol, which allows for safe and effective ACT therapy in a murine model of metastatic disease using allogeneic T cells redirected with a human EGFR2/neuregulin (Her2/neu)-specific CAR. Mild preconditioning of the recipient delayed the rejection of the allogeneic donor T cells such that they had enough time to destroy the tumor, but not enough to cause significant damage to the host. By modulating lymphocyte migration using FTY720, we were actually able to exploit the allogeneic anti-host reaction in order to augment therapeutic benefit while concurrently improving the safety of the treatment. Therefore, we suggest that CAR-based allogeneic ACT therapy could be universally used as a safe and potent ‘off-the-shelf’ treatment for cancer.     

Induction of PD-L1 on monocytes: A new mechanism by which IVIg inhibits mixed lymphocyte reactions

Allograft rejection and graft-versus-host disease (GvHD) are frequent complications following solid organ or stem cell transplantation in which T cell activation plays a central role. Despite the development of new immunosuppressive drugs that improve the success rate of transplantation, allograft survival continues to be a challenge. Recently, intravenous immunoglobulin (IVIg) has been proposed as prophylaxis and post-transplant treatment to reduce acute rejection episodes. IVIg is a therapeutic agent that is known to down-modulate T cell functions in patients with autoimmune disorders. To test the hypothesis that this immunomodulatory effect could be beneficial in the context of transplantation, we used mixed lymphocyte reactions (MLR) as an in vitro model of allograft rejection and GvHD. Our results show that IVIg strongly inhibits the MLR as evaluated by IL-2 secretion, a well-known marker of T cell activation. IVIg also modulates the secretion of other pro-(IL-6, IFN-γ) and anti-inflammatory (IL-1RA) cytokines. More importantly, we show that IVIg induces monocytes with a CD80^low PD-L1^high phenotype and that blockade of PD-L1 partially abrogates the inhibitory effect of IVIg. We have thus identified a new mechanism by which IVIg inhibits T cell functions in the context of transplantation, supporting the potential usefulness of IVIg in the prevention or treatment of graft rejection and GvHD.     

Therapy of type 1 diabetes with CD4CD25CD127-regulatory T cells prolongs survival of pancreatic islets — Results of one year follow-up

It is hypothesized that CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs) can prevent destruction of pancreatic islets protecting from type 1 diabetes (DM1).     

IL‐12/15/18‐preactivated NK cells suppress GvHD in a mouse model of mismatched hematopoietic cell transplantation

Mismatched hematopoietic cell transplants for treating leukemia are complicated by graft versus host disease (GvHD). Here, we show that adoptively transferred IL‐12/15/18‐preactivated NK cells suppress GvHD in a mouse model of fully mismatched hematopoietic cell transplantation. These IL‐12/15/18‐preactivated NK cells maintained Eomesodermin (Eomes) and T‐bet expression upon transfer and, while there was no evidence of direct killing of donor T cells or host DCs by the IL‐12/15/18‐preactivated NK cells, proliferation of donor T cells was inhibited. Strikingly, the graft versus leukemia effect mediated by donor T cells was retained, resulting in improved overall survival of mice that received lymphoma cells, donor allogeneic T cells, and IL‐12/15/18‐preactivated NK cells. These results suggest that IL‐12/15/18‐preactivated NK cells may be useful in improving immunotherapy of mismatched hematopoietic cell transplantation. Compared with previously proposed protocols, our findings suggest that in vitro NK‐cell preactivation with this cytokine cocktail offers the significant advantage that cytokines do not need to be administered systemically to sustain NK‐cell activity, thus avoiding toxicity.     

HLA-C locus allelic dropout in Sanger sequence-based typing due to intronic single nucleotide polymorphism

We report a novel HLA-C allele that was identified during routine HLA typing using sequence-based methods. The patient was initially typed as a C*06:02, 06:04 with two nucleotide mismatches in exon 3, (C to T and T to G changes) which would have resulted in a non-synonymous mutation of a leucine residue being replaced with tryptophan. Further resolution of the patient’s type by using sequence-specific primers (SSP) revealed that the companion allele to C*06:02 was a novel C*17:01. Confirmation of the existence of the new allele was performed across multiple platforms: Sanger sequencing, SSP, and Next Generation Sequencing (NGS) on the original sample and allele-specific clones for the entire HLA-C locus. The investigation revealed a single nucleotide mismatch within the Sanger sequencing primer binding site in intron 3. The mutation caused the initial C*17 dropout in exons 2 and 3. Further analysis of the Sanger and NGS data revealed that the C*17 had two additional unique positions in introns 2 and 7. The companion C*06:02 allele also possessed a novel position at intron 3. On August 31, 2013, the WHO nomenclature committee officially named the novel C*17:01 allele sequence as C*17:01:01:03 and the novel C*06:02 allele sequence as C*06:02:01:03.     

Immunomagnetic isolation of CD4+CD25+FoxP3+ natural T regulatory lymphocytes for clinical applications

Although CD4⁺/CD25⁺ T regulatory cells (T_regs) are a potentially powerful tool in bone marrow transplantation, a prerequisite for clinical use is a cell‐separation strategy complying with good manufacturing practice guidelines. We isolated T_regs from standard leukapheresis products using double‐negative selection (anti‐CD8 and anti‐CD19 monoclonal antibodies) followed by positive selection (anti‐CD25 monoclonal antibody). The final cell fraction (CD4⁺/CD25⁺) showed a mean purity of 93·6% ± 1·1. Recovery efficiency was 81·52% ± 7·4. The CD4⁺/CD25^+bright cells were 28·4% ± 6·8. The CD4⁺/CD25⁺ fraction contained a mean of 51·9% ± 15·1 FoxP3 cells and a mean of 18·9% ± 11·5 CD127 cells. Increased FoxP3 and depleted CD127 mRNAs in CD4⁺CD25⁺FoxP3⁺ cells were in line with flow cytometric results. In Vβ spectratyping the complexity scores of CD4⁺/CD25⁺ cells and CD4⁺/CD25^‐ cells were not significantly different, indicating that T_regs had a broad T cell receptor repertoire. The inhibition assay showed that CD4⁺/CD25⁺ cells inhibited CD4⁺/CD25^‐ cells in a dose‐dependent manner (mean inhibition percentages: 72·4 ± 8·9 [ratio of T responder (T_resp) to T_regs, 1:2]; 60·8% ± 20·5 (ratio of T_resp to T_regs, 1:1); 25·6 ± 19·6 (ratio of T_resp to T_regs, 1:0·1)). Our study shows that negative/positive T_reg selection, performed using the CliniMACS device and reagents, enriches significantly CD4⁺CD25⁺FoxP3⁺ cells endowed with immunosuppressive capacities. The CD4⁺CD25⁺FoxP3⁺ population is a source of natural T_reg cells that are depleted of CD8⁺ and CD4⁺/CD25^‐ reacting clones which are potentially responsible for triggering graft‐versus‐host disease (GvHD). Cells isolated by means of this approach might be used in allogeneic haematopoietic cell transplantation to facilitate engraftment and reduce the incidence and severity of GvHD without abrogating the potential graft‐versus‐tumour effect.     

Can HLA-G polymorphisms predict the development of cardiac allograft vasculopathy?

A 14 bp insertion/deletion polymorphism in exon 8 of the HLA-G gene is associated with mRNA stability and HLA-G expression. In cardiac transplantation, the 14 bp deletion polymorphism plays an important role in the expression of HLA-G and is associated with fewer episodes of cellular rejection. We investigated the association between the 14 bp insertion/deletion HLA-G polymorphism and cardiac allograft vasculopathy (CAV) post heart transplantation. There were no statistically significant differences in the presence of the three HLA-G genotypes (−14 bp/−14 bp, +14 bp/−14 bp, +14 bp/+14 bp) between patients without CAV and patients with CAV at 1 year (p = 0.61) or 5 years (p = 0.76) post-transplant. We found no correlation between HLA-G genotypes and CAV progression from baseline to 5 years post-transplant (p = 0.55). HLA-G polymorphism appears to play an important role as a genetic indicator for cellular rejection post-transplant; however, it is not a reliable marker to identify patients at risk of CAV.     

The Immunomodulatory Role of CD4-Positive Cytotoxic T-lymphocytes in Health and Disease

Among the CD4-positive (CD4+) T-lymphocytes a population exists which expresses cytolytic activity. These ‘killer’ cells belong to the T helper type 1 (Th1) subset and if activated, express Fas-ligand (FasL) which induces apoptosis in Fas-positive target cells. The major targets of these CD4+ cytotoxic T-lymphocytes (CTL) are cells of the immune system, such as T, B cells and macrophages which express Fas upon activation. Thus, CD4+ CTL play a major immunoregulatory part through the elimination of activated myeloid and lymphoid cells during and upon completion of an immune response. In certain diseases, such as in HIV-infection and some autoimmune disorders, the functional activity of CD4+ CTL is disturbed preferentially at the level of FasL-Fas interaction, further emphasizing their important immunoregulatory role. Furthermore, Fas-ligand expressing tumors can evade the attack of Fas-positive CD4+ CTL and other effector cells, thereby giving them an opportunity to expand.     

Safety of live vaccinations on immunosuppressive therapy in patients with immune-mediated inflammatory diseases,solid organ transplantation or after bone-marrow transplantation – A systematic review of randomized trials,observational studies and case reports

BackgroundLive vaccines are generally contraindicated on immunosuppressive therapy due to safety concerns. However, data are limited to corroborate this practice.ObjectivesTo estimate the safety of live vaccinations in patients with immune-mediated inflammatory diseases (IMID) or solid organ transplantation (SOT) on immunosuppressive treatment and in patients after bone-marrow transplantation (BMT).Data SourcesA search was conducted in electronic databases (Cochrane, Pubmed, Embase) and additional literature was identified by targeted searches.Eligibility criteriaRandomized trials, observational studies and case reports.PopulationPatients with IMID or SOT on immunosuppressive treatment and BMT patients <2 years after transplantation.Intervention/vaccinations looked atLive vaccinations: mumps, measles, rubella (MMR), yellow fever (YF), varicella vaccine (VV), herpes zoster (HZ), oral typhoid, oral polio, rotavirus, Bacillus Calmette–Guérin (BCG), smallpox.Data extractionOne author performed the data extraction using predefined data fields. It was cross-checked by two other authors.Results7305 articles were identified and 64 articles were included: 40 on IMID, 16 on SOT and 8 on BMT patients. In most studies, the administration of live vaccines was safe. However, some serious vaccine-related adverse events occurred. 32 participants developed an infection with the vaccine strain; in most cases the infection was mild. However, in two patients fatal infections were reported: a patient with RA/SLE overlap who started MTX/dexamethasone treatment four days after the YFV developed a yellow fever vaccine-associated viscerotropic disease (YEL-AVD) and died. The particular vaccine lot was found to be associated with a more than 20 times risk of YEL-AVD. One infant whose mother was under infliximab treatment during pregnancy received the BCG vaccine at the age of three months and developed disseminated BCG infection and died. An immunogenicity assessment was performed in 43 studies. In most cases the patients developed satisfactory seroprotection rates. In the IMID group, YFV and VV demonstrated high seroconversion rates. MTX and tumor necrosis factor inhibitory therapy appeared to reduce immune responses to VV and HZ vaccine, but not to MMR and YF-revaccination. Seroconversion in SOT and BMT patients showed mostly higher rates for rubella than for measles, mumps and varicella.LimitationsRisk of bias was high in the majority of studies since 39 of them were observational and 17 were case series/case reports. Only eight studies were randomized trials. BMT patient numbers included in this review were low.ConclusionsAlthough live vaccinations were safe and sufficiently immunogenic in most studies, some serious reactions and vaccine-related infections were reported in immunosuppressed IMID and SOT patients. Apart from mild vaccine-related infections MMR and VV vaccines were safe when administered less than two years after BMT.Implications of key findingsUntil further data are available, live vaccinations under most immunosuppressive treatments should only be administered after a careful risk benefit assessment of medications and dosages.FundingNone.