title: 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), downregulated CD45RC by day 4 and remained CD45RC- during the course of the experiment. Using mixtures of allotype-marked CD45RC+ and CD45RC- T cells, it was demonstrated that each subset showed comparable survival, IL-2R expression and time courses of activation in response to alloantigen. The repertoire of neither subset was, therefore, deficient in terms of allorecognition. The rapid re-expression of CD45RC in culture was accompanied by a change in function: CD45RC+ "converts", obtained by overnight culture of CD45RC- T cells, induced significantly higher graft-versus-host responses. Thus, the transition in culture from CD45RC- to CD45RC+ reflects a major functional reprogramming of the cell and not a trivial modulation of a surface antigen.
authors.affiliation: Department of Cell and Structural Biology, University of Manchester Medical School, GB.
authors.forename: S R
authors.initials: SR
authors.lastname: Sarawar
authors.forename: S M
authors.initials: SM
authors.lastname: Sparshott
authors.forename: P
authors.initials: P
authors.lastname: Sutton
authors.forename: C P
authors.initials: CP
authors.lastname: Yang
authors.forename: I V
authors.initials: IV
authors.lastname: Hutchinson
authors.forename: E B
authors.initials: EB
authors.lastname: Bell
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D002478:Cells, Cultured; D006087:Graft vs Host Reaction; D017493:Leukocyte Common Antigens / Q000032:analysis*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D017493:Leukocyte Common Antigens