Trait-like immunological and hematological measures in female rhesus across varied environmental conditions

In this 2-year longitudinal study, 45 2-year-old female rhesus were observe d as they were captured and removed from a free-ranging setting (Phase I), single caged for 1 year (Phase II), and housed in small, stable social grou ps for an additional year (Phase III). During the study, eight blood sample s were taken, and hematological, immunological, and hormonal variables were assayed to determine whether I) any of the measures would exhibit trait-li ke, inter-individual longitudinal stability, despite fluctuations in popula tion means induced by Phases I, II, and III; 2) plasma concentrations of co rtisol, prolactin, and norepinephrine would be lowest in Phase III, and ele vated during the periods of acute and chronic stress associated with Phases I and II; and 3) there would be any evidence of immunosuppression associat ed with Phases I and II. The results suggest that the majority of hematolog ical/immunological variables were trait-like throughout the study in contra st to plasma cortisol, prolactin, and norepinephrine concentrations. Thus, red blood cells, hemoglobin, hematocrit, platelets, mean corpuscular volume and hemoglobin, as well as white blood cells, the absolute number of CD4(T-helper/ inducer) cells, the absolute number of CD8+ (T-suppressor/cytoto xic) cells, total T cells (CD2+%), total B cells (CD20+%), and the ratio of CD4+/ CD8+ cells were trait-like. The hematological measures were changed dramatically by capture and the subsequent single caging, with most not rec overing to presumed baselines until after 12-28 weeks. The immune measures were depressed at capture (excepting B cells), and during 7 months of singl e caging failed to return to normal levels associated with social housing. We thus conclude that single housing can produce significant, long-term fea tures of Immunosuppression. Capture produced significant increases in plasm a cortisol, prolactin, and norepinephrine concentrations. Long periods of s ingle caging produced significant increases in plasma prolactin concentrati ons, indicative of stress-induced anxiety, and may also have been associate d with down-regulation of plasma norepinephrine and cortisol concentrations . (C) 1999 Wiley-Liss, Inc.