Selective Depletion of Rat Neutrophils by In Vivo Administration of a Monoclonal Antibody

A monoclonal antibody (RP‐3) that depletes rat neutrophils selectively in vivo was developed by hybridization of mouse myeloma cells (P3‐X63.Ag8.653) and spleen cells of BALB/c mice sensitized with peritoneal neutrophils of WKA/Hok rats. RP‐3 reacted with rat neutrophils but not with lymphocytes, macrophages, natural killer cells, basophils, eosinophils, or tissues of various organs. The mitogenic responsiveness to concanavalin A (ConA), phytohemagglutinin (PHA), and lipopolysaccharide (LPS) of rats given RP‐3 was not significantly different from that of normal rats. Administration of RP‐3 into the peritoneal cavity of rats that had been kept under specific pathogen‐free (SPF) or clean conditions induced selective depletion of circulating neutrophils to under 100/mm3(0.5% WBC). The numbers of monocytes, lymphocytes, and platelets were not changed. Administration of 2 ml of RP‐3 reduced blood neutrophils to under 100/mm3for approximately 24 h, and administration of 1 ml caused depletion for approximately 12 h.