In vivo expression and regulation of murine IL 2 receptors after antigen sensitization.

We have studied the in vivo regulation and expression of the murine IL 2 receptor after antigen sensitization. High and low affinity receptor expression has been studied by flow cytometry analysis and radiolabeled IL 2 binding. Both anti-IL 2 receptor antibody and unlabeled IL 2 inhibited the radiolabeled IL 2 binding. The kinetics of expression of the IL 2 receptor closely correspond to the proliferative response, as assessed by IUdR radioisotope uptake. The expression of IL 2 receptors correlated with the proliferative response profile of the murine strains surveyed during a study of responses to picryl chloride. Neither immune compromised 4-mo-old MRL/lpr mice nor athymic nude mice generated significant antigen-specific proliferative responses or IL 2 receptor expression after antigen sensitization. Mice rendered specifically unresponsive to antigen displayed reduced proliferative responses to the tolerizing antigen, as well as reduced numbers of IL 2 receptor-positive cells. Finally, the treatment of mice with immunosuppressive drugs reduced both the proliferative responses as well as the number of IL 2 receptor-positive cells. However, at the cellular level, the drugs produced different effects on IL 2 receptor expression.