Functional analysis of HLA-DP polymorphism: a crucial role for DPbeta residues 9, 11, 35, 55, 56, 69 and 84-87 in T cell allorecognition and peptide binding

Abstract

The information available on the specific function of HLA-DP and the structure-function relationships is very limited. Here, single amino acid substitutions of HLA-DPB1*02012 have been used to analyze the role of polymorphic residues of the DPbeta1 domain on DP-mediated T cell allorecognition and peptide binding. Using a panel of specific anti-HLA-DP mAb, we identified the HLA-DP residues involved in the recognition by these mAb, with a crucial role for DPbeta56 for most of the mAb assayed. Individual substitutions at residues 9, 11, 35, 55, 56 and 69 completely abrogated T cell recognition mediated by two different HLA-DPw2-allospecific T cell clones (8.3 and 8.9). Interestingly single changes at positions 9, 11, 35 and 55 of HLA-DPbeta also altered the binding of peptides AAII(12-27) and IIP(53-65), natural ligands of the HLA-DPB1*02012 molecule. Individual changes at residues located in pocket 1 (84, 85, 86 and 87 from HLA-DPbeta) led to a partial reduction in cytotoxic T lymphocyte-mediated lysis and also partially affected peptide binding. However, the simultaneous substitution of these positions completely abolished both T cell allorecognition and peptide binding, suggesting a major role for polymorphisms at pocket 1 in HLA-DP function. Molecular modeling, used to predict changes induced by amino acid substitutions, supported the functional data. Taken together, these results strongly suggest that polymorphic residues 84, 85, 86 and 87 at pocket 1, residues 9, 35 and 55 at pocket 9, and residues 11 and 69 at pockets 6 and 4 respectively play a key role in HLA-DP function, probably by modifying the way the peptide is bound within the groove of HLA-DP2 and determining changes in the conformation of the MHC-peptide complex recognized by the TCR.

Identification of Functional and Expression Polymorphisms Associated With Risk for Antineutrophil Cytoplasmic Autoantibody–Associated Vasculitis

“…To confirm the haplotypic relatedness of the 3 variants, we sequenced this region in 100 study subjects who were homozygous for the rs141530233 and rs1042169 markers. Our findings confirmed the organization of the 3 variants in 2 haplotype blocks (as shown in Supplementary Figure 6), which is consistent with the findings in prior studies of a dimorphic polymorphism (GGPM versus DEAV) at the corresponding amino acid positions 84–87 of the HLA–DPB chain 22, 26, 27.…”

HLA-associated susceptibility to childhood B-cell precursor ALL: definition and role of HLA-DPB1 supertypes

“…However, HLA class II allotype-associated peptide binding is not the property of a single PBP; rather, it is the sum of a series of key PBP forming a DP allotype-associated peptide-binding motif or 'footprint'. Polymorphisms in PBP accommodating the P1, 4, 6, and 9 amino acid anchors appear primarily to influence the DP allotype footprint (Hammer et al, 1997;Diaz et al, 2003Diaz et al, , 2005. Since pocket 9 is composed of polymorphisms in residues 9, 35, 36, 55, and 56 , we excluded this level of complexity.…”

“…Pocket 4 of DP2 is deeper, more negatively charged than DP4 , giving it a greater affinity for positively charged nonpolar aromatic residues, such as glutamine (Q), arginine (R), and lysine (K). Furthermore, glycine (G) makes pocket 1 (b84) and pocket 6 (b11) deep and hydrophilic, preferentially-binding hydrophobic and aromatic amino acids, notably phenylalanine (F), and tyrosine (Y) (Berretta et al, 2003;Diaz et al, 2003Diaz et al, , 2005. This predicts that infectious peptides with an 1 FXXKXFXXA/V 9 motif (where X is unknown, and P9 can be A or V) are likely to bind to DP2.…”

“…Using a similar approach, Castelli et al (2002) defined three DP supertype clusters with shared amino acid residues in the P1 (b84) and P6 (b11) PBP. However, the P4 peptide-binding pocket, at position b69, also makes an important contribution to antibody and peptide-binding (Arroyo et al, 1995;Chicz et al, 1997), T-cell responses (Berretta et al, 2003;Diaz et al, 2003) and disease susceptibility (Potolicchio et al, 1999;Wang et al, 1999). For this reason we clustered 430 DPB1 alleles into six supertypes based on polymorphisms in three PBP, at positions 11, 69, and 84 of the b1 domain (i.e., pockets 6, 4, and 1).…”

Expression of HLA-DP0401 Molecules for Identification of DP0401 Restricted Antigen Specific T Cells

“…HLA-DP mismatches are also linked to acute graft versus host disease and graft rejection after transplantation (19,20). Associations of certain DP alleles to autoimmune diseases have also been documented (21)(22)(23)(24). Importantly, a number of HLA-DP0401 restricted tumor antigen epitopes have been described, e.g., NY-ESO-1, MAGE-A3, and SSX-2 (25)(26)(27)(28)(29).…”