Social stress, dominance and blood cellular immunity

The impact of chronic social coexistence on distribution and function of bl ood immune cells was examined in Long Evans rats. At the beginning of a 7 d ay period of chronic coexistence (confrontation), a wall was removed betwee n two neighboring cages each consisting of a male-female pair. Winner and l oser males were classified based on differences in their defensive behavior . On day 2 and 7 of confrontation, losers showed reductions in numbers of b lood CD4 and CD8 T cells as well as profound suppression of in vitro NK act ivity and lymphocyte (LYM) proliferation. Numbers of granulocytes (GRAs) we re more than doubled. Winner males showed similar immunological alterations only on day 2 of confrontation. On day 7 most changes were reversed. The p ersistent changes in loser males may reflect a less favorable state for eff ective immune response. (C) 1999 Elsevier Science B.V. All rights reserved.