A visual assay to monitor purification of cell surface antigens reacting with monoclonal antibodies.

We have developed a visual microtiter assay to detect solubilized cell-surface antigens which react with monoclonal antibodies. The assay depends on the ability of adsorbed monoclonal antibody to bind target cells to microtiter V wells, and the inhibition of binding by antigen. We have used this assay to follow a 600-fold purification of the human lymphocyte differentiation antigen 3A1 extracted from HSB-2 cells. Antigen 3A1 is a glycoprotein with a molecular weight of approximately 40,000 daltons.