Involvement of class II beta-chain amino acid residues 85 and 86 in T-cell allorecognition.
Alloreactive T-cell clones were derived by limiting dilution following priming to allogeneic cells bearing HLA-DR1 alloantigens. Clonal specificities were determined by extensive testing on a panel of allogeneic lymphoblastoid cell lines and by blocking studies with monoclonal antibodies specific for HLA-DR, -DQ, and -DP class II molecules. Out of nine DR1-positive cell lines, three failed to stimulate a subset of the T-cell clones in conventional proliferation assays. Proliferation by all of the clones was blocked by anti-DR antibodies, not by anti-DQ or anti-DP, which was consistent with the conclusion that the HLA-DR molecule was recognized. This DR1-associated polymorphism has been identified as Dw20 by the Tenth International Histocompatibility Workshop. The molecular basis for this altered recognition of the DR1 molecule was determined by allele-specific oligonucleotide hybridization and by DNA sequencing studies. The first, second, and third hypervariable regions of all nine DR1-positive cell lines were identical. Valine and glycine were found at positions 85 and 86 of the DR1 beta 1 chain in DR1 molecules from six of the nine lymphoblastoid cell lines, whereas alanine and valine were found in the three variant (Dw20) DR1-positive cells. By analogy with class I structure, residues 85 and 86 would be located at the extreme C-terminal end of the beta-chain alpha helix. Together or separately, these amino acid differences may define a T-cell recognition element on the DR1 molecule serving to contact allospecific T-cell receptors. Alternatively, if allorecognition involves recognition of a self peptide complexed with an allogeneic MHC molecule, then it is possible that the differences T cells recognize on DR1 class II proteins arise from peptide-specific interactions with residues 85 and 86.
Immunogenetics Research Section, Blood Center of Southeastern Wisconsin, Milwaukee 53233.
D D
DD
Eckels
M J
MJ
Geiger
T W
TW
Sell
J A
JA
Gorski
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000502:physiology*; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D000939:Epitopes; D015798:HLA-DR1 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D011110:Polymorphism, Genetic / Q000235:genetics / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000596:Amino Acids; D000911:Antibodies, Monoclonal; D000939:Epitopes; D015798:HLA-DR1 Antigen; D015345:Oligonucleotide Probes; D011948:Receptors, Antigen, T-Cell