HLA-DQ-Specific Recombinant Human Monoclonal Antibodies Allow for In-Depth Analysis of HLA-DQ Epitopes

Abstract

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.

Snowflake: A deep learning-based human leukocyte antigen matching algorithm considering allele-specific surface accessibility

“…To confirm the impact of allele-specific solvent accessibility experimentally, binding analyses of HLA epitope-specific monoclonal antibodies to HLA as applied by Bezstarosti et al may be informative (36). Following the hypothesis, antibodies against antibody-verified Eplets with a wide distribution of surface accessibility (e.g.…”

A new strategy for systematically classifying HLA alleles into serological specificities

“…Critical residues defining serotypes or determining epitopes of HLA class II products were identified by similar approaches for HLA‐DR, 36–43 DQ 43–45 and DP 46–48 . Many of the epitopes defined in early studies were identified by non‐human mAbs; additional work confirmed that these same epitopes were also identified by both, allo‐antisera and mAbs of human origin 6,7,49,50 …”

“…[46][47][48] Many of the epitopes defined in early studies were identified by non-human mAbs; additional work confirmed that these same epitopes were also identified by both, allo-antisera and mAbs of human origin. 6,7,49,50 The simultaneous application of molecular typing methods and serologic testing in IHIW exercises allowed inference of which amino acids at polymorphic positions in the HLA class I and class II proteins, may determine epitopes recognized by sets of mAbs or by clusters of alloantibody reagents evaluated in the 12th 4,5 and 13th 6,7 IHIW. In the 13th IHIW the systematic computational analyses for examination of the mAbs and allo-antisera reactivity allowed mapping the putative epitopes recognized by serologic reagents.…”

A Comprehensive Evaluation of the Antibody-Verified Status of Eplets Listed in the HLA Epitope Registry

“…For these eplets, previously published SAB data were re-analyzed to determine the uniquely shared residues and subsequently the possible eplets, which led to proposed new definitions of these reactivity patterns. The list of HLA class II antibody-verified eplets and antibody-verified reactivity patterns including literature references (43)(44)(45)(46)(47)(48)(49)(50) are depicted in Tables 6 and 7 respectively.…”