Locus‐specific detection of HLA‐DQ and ‐DR antigens by antibodies against synthetic N‐terminal octapeptides of the β chain

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Abstract
Antibodies against synthetic peptides representing the class-II antigen HLA-DR and -DQ β chain N-terminal sequences were prepared in rabbits. The two octapeptides only share two amino acids and enzyme-linked immuno-assays showed the antisera only to bind to its own antigen. Both peptide antisera detected a 29 kDa component in immunoblots of Raji and AL-34 cell plasma membrane proteins separated by SDS gel electrophoresis. The binding of either N-terminal peptide antiserum was selectively inhibited only by the peptide used as antigen. Indirect immunofluorescence.analysis by flow cytofluorometry showed specific surface immunofluorescence in 1:100–1:1000 dilutions in lymphoblastoid and blood mononucleated cells. In the latter the binding was primarily confined to monocytes and a subpopulation of lymphocytes. It is concluded that locus-specific immunological reagents to distinguish between β chains of HLA-DR and -DQ have been prepared by the preparation by the production of antibodies against the N-terminal sequences of each polypeptid