Supplementary characteristics of anti-MHC class II monoclonal antibodies elicited by an ALL cell line: immunofluorescence cytofluorometry, C-dependent cytotoxicity, two-dimensional analysis of antigen.

Monoclonal antibodies directed to MHC class II antigen(s), elicited by a non-T, non-B ALL cell line, were characterized by immunofluorescence flow cytofluorometry and ELISA immunofiltration measurements of their immunoreactivity with selected neoplastic hemopoietic cell lines, determination of their complement-dependent cytotoxic activity against isolated peripheral blood B and T lymphocytes and by two-dimensional electrophoretic analysis (isoelectric focusing, SDS-PAGE) of radiolabeled, immunoprecipitated by these antibodies cell surface antigens. Patterns of these immunological reactivities, as well as two-dimensional radioimmunoprecipitation patterns (acidic heavy chain p35 and basic light chain p30) of antigens recognized by these antibodies confirm their anti-MHC class II specificity. One of these antibodies (braFB6; IgG2b) displayed identical pattern of expression on cell lines and cell types as the typical anti-MHC class II antibodies, but immunoprecipitated only a single chain p30 radioiodinated cell surface protein (with two-dimensional pattern close to the beta-chain of MHC class II DR antigen). These properties indicate the ability of braFB6 monoclonal antibody to recognize a nonpolymorphic determinant of DP-MHC class II antigen.