Corticosteroids decrease the expression of beta 2-microglobulin and histocompatibility antigens on human peripheral blood lymphocytes in vitro.

The in vitro effect of two different glucocorticoids (prednisolone and dexamethasone) on the expression of beta 2-microglobulin and HLA-A-A, -B and -C-antigens on the surface of cultured lymphocytes was measured by quantitative immunofluorescence (flow cytofluorometry) and by a radioimmunoassay. Both antigens were found to be decreased, dexamethasone typically in a concentration of 10-6 mol/l causing a decrease in surface beta 2-microglobulin of 15% after an incubation period of 24 hr. The expression of two other lymphocyte surface antigens, Igm and Thy antigens, measured in parallel with beta 2-microglobulin and HLA antigens, was not affected by the same culture conditions. The steroid effect was not due to masking of the affected antigens, but was completely abolished by inhibition of protein synthesis.