AN S-49 CELL-LINE WITH A MODIFIED GLUCOCORTICOID RECEPTOR IS DEPLETEDOF MEMBRANE-ASSOCIATED GLUCOCORTICOID RECEPTOR AND DEFICIENT IN THE LYMPHOCYTOLYTIC RESPONSE

The role of plasma membrane-associated glucocorticoid receptors (mGR) in mediating the lymphocytolytic effects of glucocorticoids was furthe r assessed using repeatedly immunoisolated S-49 cells highly enriched (mGR(++)) or very depleted (mGR(--)) for mGR. The mGR(++) cells grow i n clusters (50-200 cells) compared to individual mGR(--) cells. Immuno ananalysis by flow cytometry demonstrated abundant mGR, Thy-1.2, H-2 m ajor histocompatibility, and LFA-1 antigens present on mGR(++) cells, but only barely detectable mGR and an absence of these other plasma me mbrane antigens in the mGR(--) cells. Western and autoradiography bf e xtracted and dexamethasone mesylate affinity-labeled mGR produced an i mmunoreactive and competitively labeled receptor signal (94 KD and som e larger species) in the mGR(++) population only. Density gradient stu dies showed that a truncated form of intracellular GR was present in m GR(--) cells, and that this truncation was not due to protease activit y specific to mGR(--) cells. Hormone binding and Northern analyses dem onstrated that the total number of GR sites and GRmRNAs were similar t o 30-40% lower in mGR(--) cells. Glucocorticoid lysis sensitivity was far greater in mGR(++) cells. These results reinforce our previous con clusion that the cytolytic response to glococorticoids depends not on the total number of receptor sites, but rather on the presence of the mGR subpopulation.