CELLULAR-IMMUNITY IS NOT COMPROMISED BY HIGH SERUM CORTICOSTERONE CONCENTRATIONS IN PRAIRIE VOLES

Glucocorticoids compromise immune function in glucocorticoid-sensitive species (e.g., mice), but these immunosuppressive effects may be redu ced in glucocorticoid-resistant species. Prairie voles (Microtus ochro gaster) have been characterized as glucocorticoid-resistant to their h igh circulating levels of corticosterone. Because glucocorticoid-sensi tive species display suppressed lymphocyte proliferation in response t o elevated blood glucocorticoid levels, proliferative values were hypo thesized to be reduced in house mice (Mus musculus) compared with prai rie voles. Prairie voles exhibited significantly higher splenocyte pro liferative responses to the T cell mitogen, Concanavalin A, despite ha ving higher basal total and free serum corticosterone levels than mice . Neither total nor free serum corticosterone correlated with prolifer ative responses from either species. These data provide further eviden ce for glucocorticoid resistance in prairie voles and suggest that the interactions between the hypothalamic-pituitary-adrenal axis and the immune system in prairie voles may differ from those in mice or other glucocorticoid-sensitive species. Therefore, prairie voles may serve a s a valuable animal model for the syndrome of glucocorticoid resistanc e in humans and the role of glucocorticoids in conditions characterize d by a hyperactive immune system.