Binding of murine monoclonal antibodies to human MHC class I or II antigens increases binding sites for either antibody.
Membrane redistribution of major histocompatibility complex (MHC) class I and II antigens on human B lymphocytes and monocytes was studied quantitatively by fluorescence flow cytometry using monoclonal antibodies (mAb) w6.32 (class I-specific) and 2MC3 (class II-specific). It was shown that the surface density of class I and II antigens to which corresponding mAb had been bound decreased rapidly upon incubation at 37 degrees C. However, the total amount of class I antigens remained practically unchanged, while that of class II antigens increased substantially. This augmentation of class II antigens could be elicited not only by the corresponding class II-specific mAb but, similarly, also by non-corresponding class I-specific mAb. New expression of class I antigens only compensated for removed antigens. The speed of disappearance was comparable for antigens of either class. We conclude that the more pronounced expression of new class II antigens is not due to a greater surface mobility, but to a faster recycling and/or larger intracellular deposits of the antigens. This uneven redistribution of class I and II antigens is likely to reflect differences of function known to be dependent on MHC products.
D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D001665:Binding Sites; D006680:HLA Antigens / Q000032:analysis / Q000276:immunology*; D008285:Major Histocompatibility Complex; D051379:Mice; D009000:Monocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface; D006680:HLA Antigens