A periodicity in the response of SJL/J thymocytes to isoproterenol. Simulation by cell lines

Thymocytes from SJL/J mice exhibit a periodicity in their response to hormonal stimulation with isoproterenol. This periodicity (5-9 days) is expressed in large changes in the intensity of the response (peak levels of intracellular cAMP which vary approximately 6-fold), and in the response pattern, i.e., in the occurrence or non-occurrence of an immediate hormone-induced desensitization. In contrast, C57BL/6 thymocytes have a homogeneous response pattern (in all cases there was an immediate desensitization). Their response does change with the same periodicity, but these changes are restricted to the intensity of response (the peak of cAMP levels varies only approximately 2-fold). Using T, B and pre-B shown that these periodic changes may be due to fluctuations in T cell subpopulations in the thymus and possibly also the infiltration of B cells into it. These observations provide a useful system for studying at the cellular and molecular level the known correlation between endocrine disorders and neoplasia in mice. On the other hand, the set of cell lines with such different response patterns to a single hormone may be used for the identification and isolation of additional cellular constituents involved in the cellular response to hormones and its immediate desensitization.