Comparison of Class II HLA antigen expression in normal and carcinomatous human breast cells.

ABSTRACT

Class II HLA antigen expression in breast carcinoma and normal breast gland cells was compared using a method more accurate than immunofluorescence. This new method involves labeling membrane proteins with 131I and the anti-Class II HLA monoclonal antibody with 125I. The isolation and purification of the doubly labeled (125I-131I) immune complex was performed by affinity chromatography and chromatofocusing successively. When the specific activity of glycoproteins is known, the amount of glycoproteins which bind specifically to the anti-Class II HLA monoclonal antibody can be deduced. In breast carcinoma cells, 1.5 to 2% of the purified glycoproteins bind specifically to the monoclonal antibody, whereas less than 0.3% of normal breast gland cells binds. In contrast, leukemic cells, of which 80 to 90% possess Class II HLA antigens, 2 to 3% of Class II HLA glycoproteins bind specifically with the anti-Class II HLA monoclonal antibody.