Sodium dodecyl sulfate-resistant HLA-DR "superdimer" bands are in some cases class II heterodimers bound to antibody.
The detection of dimers of dimers in MHC class II crystals has excited speculation about their possible functions in T cell Ag recognition. Biochemical evidence for the existence of DR superdimers falls short of proof and is controversial. To monitor B lymphoma cells for high m.w. complexes of HLA-DR molecules, membrane preparations and cell lysates were screened by one- and two-dimensional Western blotting. Under these conditions, in which DRalpha beta heterodimers were readily detected, no DR complexes with an (alpha beta)2-chain composition could be identified. Two mAbs (L243 and D1-12) immunoprecipitated high m.w. DR complexes suspected to be superdimers. However, biochemical analysis revealed that, rather than superdimers, these were SDS-stable complexes of DR in combination with the Abs. Thus, previous observations of HLA-DR superdimer bands may also reflect complexes of DR molecules with bound Ab.
Hitzel
C
C
Division of Immunobiology, University of Bonn, Germany.
Grüneberg
U
U
van Ham
M
M
Trowsdale
J
J
Koch
N
N
D000911:Antibodies, Monoclonal / Q000302:isolation & purification / Q000378:metabolism; D001666:Binding Sites, Antibody / Q000187:drug effects; D002458:Cell Fractionation; D019281:Dimerization; D006684:HLA-DR Antigens / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D006684:HLA-DR Antigens; D007140:Immunoglobulin Fab Fragments; D046911:Macromolecular Substances; D012967:Sodium Dodecyl Sulfate