Interaction between the CD45 antigen and phytohemagglutinin. Inhibitory effect on the lectininduced T cell proliferation by anti‐CD45 monoclonal antibody

Abstract

Immunoprecipitation studies from ¹²⁵I‐labeled T cells, previously activated with the lectin phytohemagglutinin (PHA) from Phaseolus vulgaris, showed a preferential association between the CD45 glycoprotein family containing members of 220, 205, 190 and 180 kDa, and a protein of 33 kDa. This 33‐kDa protein, with an identical molecular mass as PHA, was not associated with other highly expressed molecules such as class I histocompatibility antigens (HLA‐A,B,C), transferrin receptor, CDw44 and CD11a. Further immunoprecipitation analysis from peripheral blood lymphocytes incubated with ¹²⁵I‐labeled PHA confirmed the identification of the CD45‐associated 33‐kDa protein as the lectin PHA. These results prompted us to analyze the possible involvement of the CD45 molecules in the T cell activation process induced by PHA. Thus, two monoclonal antibodies specific for CD45 antigens were able to inhibit the T cell proliferation induced by the lectin. This inhibitory ability was exerted by affecting both the interleukin 2 production and the interleukin 2 receptor expression.