ABSTRACT
M1/70 antibody, identifying the Mac-1 antigen, was obtained by a serendipitous route. Rats were immunized with mouse spleen cells and 10 cloned hybridoma lines were obtained. Screening on a tumor cell panel revealed that the P388D1 macrophage-like cell line bound 100-fold more M1/70 antibody than spleen cells, but a series of B and T lymphoid lines gave no significant binding. The resultant multispecific response may then be resolved by cloning into a set of hybrid lines each secreting a monoclonal antibody (MAb) recognizing a single antigenic determinant on a single cell surface molecule. M1/70 also cross-reacts with an antigen on human monocytes, granulocytes, and natural killer and antibody-dependent cytotoxic cells. Immunization with whole peritoneal exudate cells resulted in comparable titers of antibodies to Mac-1, human serum albumin, and common leukocyte antigen as determined by competitive inhibition of the binding of H-labeled MAb to target cells.
