Effect of Alternate-Day Hydrocortisone Therapy on the Immunologically Immature Rat. III: Changes in T- and B-Cell Areas in Lymph Nodes

Abstract

ABSTKACTThe histologic effects of the alternate-day hydrocortisone therapy (400 mg/M2 from day 7 to day 19 after birth) were studied on the mesenteric lymph nodes of immunologically immature rats. In rats sacrificed 2 days following the cessation of therapy, depletion of lymphocytes of the thymus-independent area was apparent. Smaller lymphocytes were more susceptible to the effect of hydrocortisone than larger ones. The absence of primary follicles, normally present at this age, suggested a possible retardation in development of the immune system. B lymphocytes appeared to be the target of the direct lymphocytolytic effect of hydrocortisone. In rats sacrificed 23 days following the treatment, immunological maturity was achieved, indicating the reversibility of the hydrocortisone effect.

Electron Microscopic Study on the Effect of Alternate-Day Hydrocortisone Therapy on Lymphocyte Populations in Rat Spleen and Lymph Nodes

“…Previous studies (7,8) have been conducted to assess the immunosuppressive effects and reversibility of chronic, alternate-day hydrocortisone ther-apy on the immunologically immature rat, a steroidsensitive species (3). Alternate-day administration of hydrocortisone from days 7 through 19 from birth resulted in a depletion of small lymphocytes in the white pulp of the spleen and the cortex of the mesenteric lymph nodes when animals were sacrificed 2 days after the cessation of treatment.…”