SELECTIVE ASSOCIATION OF A 22-38-KDA GLYCOPROTEIN WITH MHC-CLASS-II DP-ANTIGEN ON ACTIVATED HUMAN-LYMPHOCYTES AT THE PLASMA-MEMBRANE

Two-dimensional electrophoretic analysis (2D-PAGE) of cell surface hum an DP and DR class II antigens identified a glycoprotein, designated p X, that is associated at the cell surface with DP but not DR class II antigen in activated T, B and Mt lymphocytes but not in resting B lymp hocytes, Raji B lymphoma cells, activated thymic epithelial cells or a ctivated monocytes. pX is a heavily glycosylated protein with an appar ent molecular mass spanning between 38 kDa and 22 kDa, that is reduced , after deglycosylation with Endo-F, to 22 kDa. The pX structure appea rs nonpolymorphic and independent of DP polymorphism, as suggested by 2D-PAGE migrational pattern of I-125-labelled Endo-F deglycosylated DP immunoprecipitates from T cell blasts derived from four donors with d ifferent DP allotypes. The apparent absence of polymorphism of pX is f urther suggested by two-dimensional peptide mapping of a single spot d erived from 2D-PAGE of I-125-labelled DP deglycosylated immunoprecipit ates from two donors. Copyright (C) 1996 Elsevier Science Ltd.