REgulation of the primary immune response in vivo by parathyroid hormone

Injection of sheep red blood cells into rats stimulates splenic DNA synthesis, then increases the proportion of plaque-forming cells, and finally raises the circulating antibody level. Removal of the parathyroid glands, which causes hypocalcemia, 24 hr before antigen injection impairs all of these responses, but is without effect after antigen injection. It is suggested that parathyroid hormone and calcium control the immune response, probably by affecting the proliferative phase of this response.