HLA‐DPp residue 69 plays a crucial role in allorecognition

Abstract

To investigate the contribution to allorecognition of the individual polymorphic positions Glu 69 and Val 36 from the DPB1*02012 allele, DPB1*02012 cDNA was subjected to site-directed mutagenesis and alleles expressing Lys at 69 and Ala at 36 were generated. The lymphoblastoid cell line (LCL) 45.EM1, a previously generated mutant B-LCL which expresses normal levels of DPA mRNA but is not able to transcribe DPB, was transfected with wild-type or mutant DPB1*02012 cDNAs. The ability of two HLA-DPw2 alloreactive CD4+ cytotoxic T-lymphocyte (CTL) clones to lyse the panel of DPB1*02012 wild-type and site-directed mutant B-cell lines was tested. Both CTL clones (8.3 and 8.9) lysed the B-LCL 45.1, which is haploid for HLA and expresses wild-type DPB1*02012, and transfectants expressing Ala at 36 instead of Val, indicating that this polymorphic residue is not critical for T-cell recognition. However, the change of Glu to Lys at 69 prevented recognition by clones 8.3 and 8.9. These data demonstrate that the residue at peptide-binding position 69 is crucial for T-cell receptor recognition and suggest the requirement for a negatively charged residue at this position for allostimulation of these T-cell clones. The side chain of DPbeta-69 is predicted to point into the peptide-binding groove, and the existence of positive(Lys) or negative (Glu) residues probably leads to substantial differences in the allo- or auto-DP-bound peptides or to differences in the conformation of the peptide-MHC complex, which would therefore be responsible for specific DPw2 allorecognition. The binding of a panel of monomorphic and polymorphic anti-HLA-DP monoclonal antibodies (mAbs) to these transfectants was also tested by flow cytometry. The changes at Glu 69 and Val 36 did not affect recognition by any of the monomorphic antibodies tested. However, the binding pattern of some of the polymorphic mAbs was clearly modified. Therefore, even though it is not crucial for T-cell allorecognition, polymorphic residue 36 must be involved in epitopes recognized by some polymorphic anti-DP antibodies, while residue 69 of the DPB molecule is crucial both for T-cell allorecognition and recognition by some mAbs.

Major histocompatibility locus genetic markers of beryllium sensitization and disease

“…In the present study, increased frequencies of Glu69 HLA-DPB1 alleles, including HLA-DPB1*0201, were also found both in the "sensitized" and the "disease case" groups. However, the demonstration by LOMBARDI et al [8] that the Glu69 residue of the HLA-DP b chain is directly involved in presentation of Be to the T-cells of HLA-DPBGlu69 subjects with berylliosis, consistent with the observation that the HLA-DPGlu69 residue is important in autoimmunity and alloreactivity [20] and with the finding of oligoclonal beryllium-reactive T-cells [21], strongly indicates that the sequence coding for the HLA-DPB1 amino acid residue Glu69 is not only a supratypic marker but it is the immune response gene of berylliosis. Interestingly, the observation that HLA-DPGlu69 is associated with susceptibility to hard metal lung disease and that cobalt directly interacts with the HLA-DPB1Glu69 molecule [22] suggests that this HLA-DP molecule is endowed with the ability of interacting with certain metal cations, possibly through direct binding.…”

DPB1 disparities contribute to severe GVHD and reduced patient survival after unrelated donor bone marrow transplantation

“…The biological significance of each HVR matching on GVHD and survival was tested and no correlation was observed. Whilst it appears that glutamic acid at position 69 (E69) in the DP␤1 molecule is a key residue in the alloimmune response [17][18][19] and antigen presentation, 20 we did not detect any effect of E69 incompatibility on either survival or acute GVHD.…”

The Impact of Amino Acid Variability on Alloreactivity Defines a Functional Distance Predictive of Permissive HLA-DPB1 Mismatches in Hematopoietic Stem Cell Transplantation

“…We therefore used HLA-DPB1*09:01 as reference allele for SDM of polymorphic aa in the a2 domain encoded by exon 2. A total of 10 polymorphic aa residues within hypervariable regions A through F, located at position 8,9,11,35,55, 56, 57, 69, 76, and 84, were swapped into a residue naturally encoded by other HLA-DPB1 alleles, resulting in a total of 12 point mutants of HLA-DPB1*09:01 ( Table 1) (Table 1), or with irrelevant control HLA-DPB1 (CTR), by clonal alloreactive CD4 þ T cells (Table S2). CTR was HLA-DPB1*01:01 for MGAR and HLA-DPB1*04:01 for VAVY.…”