Modulation of class I HLA antigens on HL-60 promyelocytic leukemia cells by serum-free medium: re-induction by gamma-IFN and 1,25-dihydroxyvitamin D3 (calcitriol).

During studies on the effect of different nutrient media on the growth and differentiation of the HL-60 promyelocytic leukemia cell line, we found that the density of the class I HLA antigens is profoundly decreased on cells cultured in a serum-free medium. The ability of recombinant DNA-derived interferons (IFN) and a number of myeloid differentiating agents to induce re-expression of class I HLA antigens and beta-2-m was therefore studied. All three classes (alpha, beta, and gamma) of IFN were capable of re-inducing HLA and beta-2-m, although gamma-IFN was more potent. Of a variety of chemical differentiating agents, only 1,25-dihydroxyvitamin D3 (calcitriol) was found to induce HLA class I antigens. These results suggest that HLA and beta-2-m are not necessarily constitutive cell surface proteins, but instead that their expression is highly inducible.