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

Abstract

The histologic effect of 400 mg/M*/day of hydrocortisone, given alternatively from day 7 to day 19 after birth, was studied on the spleen of the immunologically immature rat. Two days after the cessation of treatment, the penarteriolar lymphatic sheaths were found to be largely depleted of small lymphocytes. Immunoperoxidase studies confirmed a depletion of T lymphocytes. The effects of hydrocortisone on the thymus seem to be more important than its direct lymphocytolytic effect in producing this splenic lesion. In contrast, no apparent change in the number of medium-sized B lymphocytes in the marginal zone was detected. Medium-sized B lymphocytes of the spleen, reported to be responsible for IgM synthesis, appeared to be subjected to a different mechanism of hydrocortisone action, other than lysis, resulting in a decrease in antibody production. Primary folliclcs were not seen in spleens of hydrocortisone-treated rats. Twentythree days after treatment, spleens had a histologically normal appearance.Keywords. Lcwis rat; hydrocortisone sc; spleen; histology; T and B lymphocytes; immunoperoxidase INTRODUC~~ON In the previous article, we showed that immunologically immature rats treated with alternate-day hydrocortisone followed by a recovery period suffered from overall growth retardation, undergrowth followed by overgrowth of the thymus and spleen, slowly reversible Iymphocytopenia, and reduced IgM concentrations.The effect of hydrocortisone on the immature immune system may be partially due to its action on the thymus (6) as well as a possible direct effect on antibody-forming cells in tissues.To complete the picture, it is necessary to investigate the effect of such a regimen on lymphoid organs. Many studies have confirmed the destructiveeffects of corticosteroid on lymphoid tissue of steroid-sensitive species (2, 1 I , 12). Others have reported the sensitivity of small lymphocytes present in lymphoid organs to the effect of hydrocortisone (1, 14). In the present article, the effect of alternateday hydrocortisone therapy on the histology of the

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

“…x 18,500. on these small lymphocytes. Rather, these findings are consistent with a depletion in the supply of T lymphocytes to the spleen resulting indirectly by the lytic effects of hydrocortisone upon the thymus (7,9).…”

“…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.…”

Neurosteroid, Natural and Anabolic Steroids: Physiological, Immunological and Histopathological Study on Diabetic Albino Rats

“…Furthermore, glucocorticoids suppress the production of prostaglandin and arachidonic acid, which causes hepatic sinusoidal dilatation and congestion [66]. Hydrocortisone treatment causes severe atrophy of splenic white pulp tissue through destroying the tissues and causes diminution of lymphocytes, especially T type lymphocytes and spleen tissue seems quite depleted from T lymphocytes [65,67].…”