IMPACT OF SOCIAL CONFRONTATION ON RAT CD4 T-CELLS BEARING DIFFERENT CD45R ISOFORMS

The impact of social defeat on lymphocyte subpopulations and T helper subsets was investigated in Long Evans rats. CD4 T helper cell subsets with distinct functional properties and different cytokine profiles c an be distinguished by using the mAbs OX-22 (anti-CD45RC) and OX-7 (an ti-CD90, Thy1.1). Male intruders were exposed for 2, 6, or 48 h to agg ressive resident pairs. All intruders were attacked upon introduction and were defeated as indicated by frequent display of full submissive postures. After 2 and 18 h of confrontation, drastic but differential effects on blood leukocyte numbers, CD4 and CD8a cells, and CD4 subset s were evident. However, after 6 h of confrontation most lymphocyte su bset numbers corresponded to baseline levels. Focusing on CD4 subsets after 7, h of confrontation, we demonstrated that only the number of t he CD45RC(-)CD90(-) subset declines, whereas neither the number of the CD45RC(+)CD90(-) subset nor the number of the CD45RC(-)CD90(+) subset (recent thymic emigrants) was influenced. Con A stimulation of sorted subsets identified the CD45RC(-)CD90(-) as a poor producer of IFN-gam ma. The data clearly demonstrate that social factors might differentia lly influence not only T cell subsets but also T helper cell subsets w ith distinct cytokine profiles in a possibly time-dependent manner. Su ch a stress-induced shift toward a CD45RC(+)CCD90(-)dominated milieu m ay have important consequences in interpreting results obtained from m itogenic stimulation of blood lymphocytes and cytokine production prof iles measured after such a stimulation. In addition, a shift toward a CD45RC(+)CD90(-) dominance may modify the type and magnitude of immune response, at least temporarily. (C) 1996 Academic Press.