Corticosteroids decrease the expression of β2-microglobulin and histocompatibility antigens on human peripheral blood lymphocytes <em>in vitro</em>.

The in vitro effect of two different glucocorticoids (prednisolone and dexamethasone) on the expression of β₂-microglobulin and HLA-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/1 causing a decrease in surface β₂-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 β₂-microglobulin and H LA 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. [ABSTRACT FROM AUTHOR]