Identification and monitoring of effector and regulatory T cells during experimental arthritis based on differential

Abstract: Major problems in the analysis of CD4 effector cell and regulatory T cell (Treg) popula-tions in an activated immune system are caused by the facts that both cell types can express CD25 and that the discriminatory marker forkhead box p3 can only be analyzed in nonviable (permeabilized) cells. Here, we show that CD134 (OX40) can be used as a discriminatory marker combined with CD25 to isolate and characterize viable CD4 ef-fector cells and Tregs. Before and during adjuvant arthritis in rats, coexpression of CD134 and CD25 identified activated Tregs consistently, as these T cells proliferated poorly to disease-associated anti-gens and were suppressive in vitro and in vivo. Depending on the time of isolation and location, CD4 T cell populations expressing CD134 or CD25 contained effector/memory T cells. Analysis of the function, phenotype, and amount of the CD4 T cell subsets in different lymph node sta-tions revealed spatiotemporal differences in effec-tor cell and Treg compartments during experimen-tal arthritis. J. Leukoc. Biol. 83: 112–121; 2008. Key Words: FoxP3 immune regulation kinetics lymph node