Hydrocortisone and the antibody response in mice. I. Correlations between serum cortisol levels and cell numbers in thymus, spleen, marrow and lymph nodes.

Mice injected with a single well tolerated dose of hydrocortisone acetate were observed over 2--3 weeks for serum cortisol levels and for cell depletion in thymus, spleen, femoral marrow, mesenteric, inguinal and popliteal lymph nodes. Serum cortisol peaked within 24 h and declined to normal after 4 days. Total marrow cell numbers were relatively unaffected, but in all other tissues studied, cell depletion was severe and prolonged. B lymphocytes were affected more severely than T lymphocytes. There was a transient increase in the percentage of marrow T lymphocytes but otherwise little change. The percentage of node T lymphocytes increased while that of B lymphocytes decreased. The percentage of spleen B lymphocytes was reduced severely but transiently during the period of serum cortisol elevation. Spleen T lymphocyte percentages rose steadily between the fourth and seventh days after treatment, then returned to normal. Representatives of most types of lymphoid tissue were studied. As cell losses in any one were not compensated by gains in any other, most were probably due to destruction rather than redistribution. The slow rates of recovery were also more consistent with regeneration than with reappearance after redistribution.