Response to prednisolone of cultured immunoglobulin-producing human lymphoid cells.

The survival of asynchronously growing lymphoid cells (T, cells) in vitro decreased to 50% viability after 1 hr treatment with concentrations of prednisolone above 10 ftg/ml. Treatment with prednisolone for 24 hr produced a decrease in cell survival to a plateau of 30% viability for concentrations above 10 ig/ml. After 48 hr treatment, 10 ig/ml prednisolone reduced viability to 12%. Synchronously growing T, cells were least sensitive to prednisolone treatment (50 ,tig/ml) during S phase (DNA synthesis period) and most sensitive during G, (pre-DNA-synthesis period). This cell cycle specificity is postulated to be an explanation for the presence of prednisolone-resistant cells in asynchronously growing populations. Immunofluorescence studies on the effect of prednisolone (100 g/ml) on immunoglobulin production indicated there was no correlation between the length of drug treatment and reduction in the percentage of immunoglobulin-producing cells. These results suggest that th. mechanism of prednisolone-induced immunosuppression in lymphoid cells is primarily lymphop.nia. C ORTICOSTEROIDS HAVE BEEN shown to produce a general suppression of the immune response, probably caused by the rapid atrophy of lymphoid structures after administration of the drug.’ This is particularly evident in the thymus where cortisone treatment destroys approximately 95% of the lymphocytes (T cells).2 However, the remaining cortisone-resistant T cells are tenfold more reactive in producing graft-versus-host responses than whole thymus cells from untreated donors.3 Lymphoid cells of the thymus-independent series (B cells) also exhibit variations in corticosteroid sensitivity. B cells found in the bone marrow are cortisone resistant, while B cells of peripheral lymphoid organs are cortisone sensitive.4’5 To better understand the effect of corticosteroids upon lymphocytes, we have investigated the response of an immunoglobulin-producing human lymphoma cell line grown in vitro to treatment by a corticosteroid analog, prednisolone.