This is an open access article under the terms of the Creat ive Commo ns Attri butio n NonCo mmercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

HLA-DQ donor-specific antibodies (DSA) are the most prevalent type of DSA after renal transplantation and have been associated with eplet mismatches between donor and recipient HLA. Eplets are theoretically defined configurations of surface exposed amino acids on HLA molecules that require verification to confirm that they can be recognized by alloantibodies and are therefore clinically relevant. In this study, we isolated HLA-DQ specific memory B cells from immunized individuals by using biotinylated HLA-DQ monomers to generate 15 recombinant human HLA-DQ specific monoclonal antibodies (mAb) with six distinct specificities. Single antigen bead reactivity patterns were analyzed with HLA-EMMA to identify amino acids that were uniquely shared by the reactive HLA alleles to define functional epitopes which were mapped to known eplets. The HLA-DQB1*03:01-specific mAb LB_DQB0301_A and the HLA-DQB1*03-specific mAb LB_DQB0303_C supported the antibody-verification of eplets 45EV and 55PP respectively, while mAbs LB_DQB0402_A and LB_DQB0602_B verified eplet 55R on HLA-DQB1*04/05/06. For three mAbs, multiple uniquely shared amino acid configurations were identified, warranting further studies to define the inducing functional epitope and corresponding eplet. Our unique set of HLA-DQ specific mAbs will be further expanded and will facilitate the in-depth analysis of HLA-DQ epitopes, which is relevant for further studies of HLA-DQ alloantibody pathogenicity in transplantation.

Soluble HLA‐G (sHLA‐G) levels in human seminal plasma (SP) can be diverse and may affect the establishment of maternal‐fetal tolerance and thereby the outcome of pregnancy. We investigated whether sHLA‐G levels in SP are associated with polymorphisms in the 3′‐untranslated region (UTR) and UTR haplotypes of the HLA‐G gene. Furthermore, we compared the HLA‐G genotype distribution and sHLA‐G levels between men, whose partner experienced unexplained recurrent miscarriage (RM), and controls. Soluble HLA‐G levels (n = 156) and HLA‐G genotyping (n = 176) were determined in SP samples. The concentration of sHLA‐G was significantly associated with several single‐nucleotide polymorphisms (SNPs): the 14 base pair (bp) insertion/deletion (indel), +3010, +3142, +3187, +3196, and + 3509. High levels of sHLA‐G were associated with UTR‐1 and low levels with UTR‐2, UTR‐4, and UTR‐7 (P < .0001). HLA‐G genotype distribution and sHLA‐G levels in SP were not significantly different between the RM group (n = 44) and controls (n = 31). In conclusion, seminal sHLA‐G levels are associated with both singular SNPs and 3UTR haplotypes. HLA‐G genotype and sHLA‐G levels in SP are not different between men whose partner experienced RM and controls, indicating that miscarriages are not solely the result of low sHLA‐G levels in SP. Instead, it is more likely that these miscarriages are the result of a multifactorial immunologic mechanism, whereby the HLA‐G 3′UTR 14 bp ins/ins genotype plays a role in a proportion of the cases. Future studies should look into the functions of sHLA‐G in SP and the consequences of low or high levels on the chance to conceive.