Developmental Changes of Immunoglobulins in Rats Treated Neonatally with Hydrocortisone

Abstract

Serum globulin and Ig[immunoglobulin]G levels were measured by radial immunodiffusion from 3-75 days after birth in rats neonatally treated with 1 mg of cortisol acetate. In controls globulins rose steadily during suckling, peaked at 11 days and remained high until weaning, when they dropped considerably. Thereafter, they rose steadily until 75 days. In treated animals levels increased slowly during development and were significantly lower than controls until 30 days. Serum IgG followed a similar pattern. The most severe immunological deficit in runts began on day 12. The most marked mortality in treated rats began at this age and in part may be due to the severe immunological impairment. No difference was detected in absorption of IgG from the gastrointestinal tract of the 2 groups. Dramatic deficits were demonstrated in the ability of treated rats to synthesize antibody when sensitized with a T [thymus-derived] cell-dependent antigen. The difference in immunological competence is due to endogenous deficits produced by a single injection of cortisol acetate at birth.