[Reverse relationship between mitogenic activity and suppressibility of glucocorticoids in human lymphocyte...

Following the intravenous injection of methylprednisolone (MP), both the number of circulating lymphocytes and their responses to T cell mitogens were decreased. They reached the lowest level 4-8 hr after injection. The degree of MP suppression of cell proliferation was greater at suboptimal mitogen concentration than at optimal one, and was grater in Con A cultures than in PHA cultures. For in vitro experiments, MP suppressed lymphocyte proliferation in a dose-dependent pattern. Similar to the results of in vivo experiments, the degree of MP suppression of cell proliferation was greater at suboptimal mitogen concentration than at optimal one, and was greater in Con A cultures than in PHA cultures. Both in vivo and in vitro results indicate the degree of MP suppression of lymphocyte proliferation was increased on exposure to weaker mitogenic activity. The mechanisms involved were discussed in detail.