XENOGENEIC MONOCLONAL-ANTIBODIES TO CELL-SURFACE ANTIGENS OF EQUINE LYMPHOCYTES

Abstract

Monoclonal antibodies to equine lymphocyte antigens were produced, using normal peripheral blood lymphocytes as the immunogen and standard hybridoma techniques. Antibody producing hybridomas were detected by a solid-phase enzyme-linked immunsorbent assay [ELISA]. Antibodies produced by 6 cloned hybrids were characterized further by microlymphocytotoxicity, indirect immunofluorescence and agglutination assays on peripheral blood lymphocytes, platelets and erythrocytes. Reaction patterns on leukocytes indicated that these antibodies may recognize at least 3 different cell-surface antigens: an antigen present on most peripheral blood lymphocytes and on platelets; an antigen present on most peripheral blood lymphocytes, but absent from platelets; and an antigen expressed by a major subpopulation of lymphocytes and also present on platelets. This last antigen is polymorphic and is expressed on the lymphocytes of .apprx. 75% of horses. The distribution of this polymorphic antigen did not correlate with the antigen distribution of any of the defined antigens of the equine major histocompatibility system. None of the 6 monoclonal antibodies reacted with antigens expressed on erythrocytes. Thus, monoclonal antibodies may be useful for the identification and characterization of various leukocyte antigens in the horse.