MRC OX-22, a monoclonal antibody that labels a new subset of T lymphocytes and reacts with the high molecular weight form of the leukocyte-common antigen.

Abstract

A mouse monoclonal antibody (MRC OX-22) is described that labels rat T cells which mediate graft-vs.-host reactions and those responsible for the suppression of antibody synthesis in hosts undergoing these reactions. Most of the T cells that provide help for B cells are MRC OX-22 negative. The rat evidently contains at least 3 phenotypically and functionally distinct subsets of T cells. The MRC OX-22 antibody also labels all B cells, 50% of bone marrow cells, but only 2% of thymocytes. Of these latter cells about half are found at the edge of the medulla and the remainder are randomly distributed throughout the cortex and medulla. Apparently, mature thymocytes leave the thymus at the cortico-medullary junction, and both cortex and medulla may be sites where thymocytes mature. Biochemical studies showed that the MRC OX-22 antibody reacts with the high MW form of the leukocyte-common antigen (L-CA). Comparison with data on human L-CA sugests that the molecular and antigenic heterogeneity of this set of glycoproteins was conserved between rat and man.