The quantitation of cell surface antigens by antibody-complement mediated cytotoxicity: application to murine...

51Cr-antibody-complement mediated cytotoxicity (ACC) can be used to quantify nanogram amounts of cell surface antigens. When pure antigen is available for calibration, inhibition of ACC by known amounts of antigen and by whole cells yields an estimate of the number of antigenic equivalents per cell. ACC is more suitable for this purpose than radioimmunoprecipitation assay. By ACC the number of antigenic equivalents of the oncornaviral proteins gp70 and p30 has been determined on the surface of various cells infected with Rauscher and Gross murine leukemia viruses.