Human Ia-like antigens (Analysis of the tissue distribution and immunochemical profile with monoclonal antibodies).

Analysis of the tissue distribution of human Ia-like antigens has shown that they have a wider distribution than originally reported. Furthermore, the expression of Ia-like antigens may change when cells undergo malignant transformation: for instance, melanoma cells acquire Ia-like antigens, while breast carcinoma cells lose them. Serological and immunochemical analysis of Ia-like antigens with monoclonal antibodies has shown a cellular and molecular heterogeneity of these molecules which had not been previously recognized with conventional allo- and xenoantisera. The functional significance of this heterogeneity is not known. Monoclonal antibodies to human Ia-like antigens cross-react with lymphocytes from other animal species indicating that portions of the molecules have been conserved during evolution. The biological implications of these findings are discussed.