Rapid re‐expression of CD45RC on rat CD4 T cells in vitro correlates with a change in function

Abstract

Rat CD4+ T cells are divided phenotypically by the anti‐CD45RC monoclonal antibody OX22 into subsets with contrasting functions. Stimulation of T cells in vitro is known to induce a change in isoform from CD45RC+ to CD45RC−. We have investigated the in vitro conditions which promote a switch in isoform in the opposite direction. We observed that a majority of CD45RC− CD4 T cells (> 90%) spontaneously re‐expressed CD45RC during the first 1‐3 days of culture in both the presence and absence of alloantigen. The T cells remained CD45RC+ when cultured for 7 days in serum‐free growth medium. However, alloantigen‐activated lymphocytes, expressing the interleukin‐2 receptor (IL‐2R), down‐regulated C..