HLA mismatching and minimization of immunosuppression are two major risk factors for the development of de novo donor specific antibodies, which is associated with reduced kidney graft survival. Antibodies do not recognize whole HLA antigens but rather individual epitopes, which are short sequences of amino acids in accessible positions. However, compatibility is still assessed by the simple count of mismatched HLA antigens. We hypothesized that the number of mismatched epitopes, or ("epitope load") would identify patients at the highest risk of developing donor specific antibodies following minimization of immunosuppression. We determined epitope load in 89 clinical trial participants who converted from cyclosporine to everolimus 3 months after kidney transplantation. Twentynine participants (32.6%) developed de novo donor specific antibodies. Compared to the number of HLA mismatches, epitope load was more strongly associated with the development of donor specific antibodies. Participants with an epitope load greater than 27 had a 12-fold relative risk of developing donor-specific antibodies compared to those with an epitope load below that threshold. Using that threshold, epitope load would have missed only one participant who subsequently developed donor specific antibodies, compared to 8 missed cases based on a 6-antigen mismatch. DQ7 was the most frequent antigenic target of donor specific antibodies in our population, and some DQ7 epitopes appeared to be more frequently involved than others. Assessing epitope load before minimizing immunosuppression may be a more efficient tool to identify patients at the highest risk of allosensitization.

No abstract

No abstract

Infections should be considered as an aggravating factor during the course of TTP. Particular polymorphisms in TLR-9 gene may represent risk factors for TTP.

Background: Human leukocyte antigen-G (HLA-G) molecules play a prominent role in immune tolerance. Structurally similar to their classical HLA homologs, they are distinct by having high rate of polymorphism in the non-coding regions including a functionally relevant 14-base pair (bp) insertion/deletion (Ins/Del) allele in the 3′ untranslated region (3′UTR), rarely examined in a hematopoietic stem cell transplantation (HSCT) setting. Here, we analyzed the potential impact of HLA-G Ins/Del dimorphism on the incidence of acute graft-versus-host disease (aGvHD), transplant-related mortality (TRM), overall survival (OS), and incidence of relapse after HSCT using bone marrow (BM) as stem cell source from HLA-matched donors. Methods: One hundred fifty-seven sibling pairs, who had undergone HSCT, were studied for the distribution of the HLA-G 14 bp Ins/Del polymorphism using a polymerase chain reaction (PCR)-based technique. Potential genetic association with the incidence of aGvHD, TRM, and OS was analyzed by monovariate and multivariate analyses. Results: Monovariate analysis showed that the homozygous state for the 14-bp Ins allele is a risk factor for severe aGvHD (grade III and IV; P = 0.008), confirmed subsequently by multivariate analysis [hazard ratio (HR) = 3.5; 95% confidence interval (95%CI) = 1.3–9.5; P = 0.012]. We did not find any association between HLA-G polymorphism and the other studied complications. Conclusion: Our data suggest that the HLA-G low expressor 14 bp Ins allele constitutes a risk factor for the incidence of severe aGvHD in patients who received BM as stem cell source.

Introduction: Toll-like receptors (TLRs) 2, 4, and the vitamin D receptor (VDR) are central components of the innate and adaptive immunity against Mycobacterium tuberculosis (Mtb). TLR2, TLR4, and VDR polymorphisms were previously associated with tuberculosis (TB) and were here investigated as candidates for pulmonary TB (PTB) susceptibility in a Moroccan population group. Methodology: Genomic DNA from 343 PTB patients and 203 healthy controls were analyzed for 12 single nucleotide polymorphisms (SNPs) located in TLR2, TLR4, and VDR genes using polymerase chain reaction-based restriction fragment length polymorphism and TaqMan SNP genotyping assays. Results: The TLR2 +597 CT genotype was associated with protection against PTB (corrected p [pc] = 0.04; odds ratio (OR) = 0.65; 95% confidence interval (CI) = 0.45 -0.94), and the TLR4 +7263 C allele was significantly associated with PTB susceptibility (pc = 0.04; OR = 1.63; CI = 1.06 -2.57). The VDR [f,b,a,T] haplotype was found to confer protection (pc < 0.00001; OR = 0.18; CI = 0.09 -0.35), while the TLR2 [-16934T,+597C,+1349T] haplotype seemed to be at risk (p = 0.03; OR = 1.52; CI = 1.01 -2.30), but statistical significance was not reached. Finally, cross-analysis between polymorphisms of the three studied genes revealed significant interaction between TLR2 +597 and TLR4 +4434 SNPs towards protection against PTB (pc = 0.036), suggesting that the functionally relevant TLR4 +4434 SNP may act synergistically with TLR2 SNPs. Conclusions: TLR2 and TLR4 interaction and a specific VDR haplotype influence protection against PTB in Moroccans patients.

Implication of immune processes in bipolar disorder (BD) has recently gained increasing attention. Tolerogenic molecules, among which HLA-G plays a prominent role, mediate the modulation of such processes. The HLA-G locus is characterized by a high number of polymorphisms including a functionally relevant 14 base pair (bp) insertion/deletion (Ins/Del) allele affecting the HLA-G expression. Here, we analyzed the distribution of this polymorphism in 561 BD patients and 161 healthy and found that the HLA-G 14bp Ins/Ins genotype was significantly more prevalent in healthy controls than in patients (corrected p; pc=0.032) and that the prevalence of such protective genotype is lower among patients born during the winter season as compared to those born in other periods (pc=0.006). Possible mechanisms between low HLA G expression and resistance to infections as well as potential relationships between infections in early life and susceptibility to BD are discussed.

No abstract