Regulation of humoral immunity in rats by pituitary hormones

Abstract

Hypophysectomized female Fischer 344 and Wistar-Furth rats had severely impaired primary and secondary antibody responses to sheep red blood cells (SRBC). Mercaptoethanol-sensitive (IgM) and mercaptoethanol-resistant (IgG) antibodies were similarly affected. Titers to Escherichia coli 055:B5 lipopolysaccharide were also significantly decreased in such animals. The antibody response of hypophysectomized rats could be restored by syngeneic pituitary grafts when placed under the kidney capsule or by prolactin treatment. Growth hormone was less effective in this respect than prolactin. Treatment of normal rats with ACTH suppressed their antibody formation to SRBC. The pituitary gland apparently has the potential to regulate humoral immune responses.