Gamma Interferon‐Induced Expression of Class II Major Histocompatibility Complex Antigens by Human Keratinocytes Effects of Conditions of Culture

Abstract

Normal human keratinocytes grown in MCDB 153 plus bovine pituitary extract and treated with recombinant gamma interferon (rIFN-gamma) express HLA-DR, DP and DQ antigens. The expression of these class II MHC antigens is time dependent: DR and DP appear before DQ. The delay in HLA-DQ expression is not due to the effects of trypsinization of cultures prior to analysis. Increasing the calcium ion concentration from 0.1 to 1.8 mM does not alter the expression of these antigens. Keratinocytes grown without serum proteins or bovine pituitary extract exhibited markedly delayed expression of DR. By contrast, keratinocytes grown in Dulbecco's modified Eagle's medium (DMEM) plus 10% fetal calf serum express DR and DP but only very small amounts of DQ after treatment with rIFN-gamma. Expression of HLA-DR occurs at doses of rIFN-gamma that are too low to cause growth inhibition. The cells of the squamous cell carcinoma cell line SCL-1, whether grown in MCDB 153 plus bovine pituitary extract or DMEM plus 10% fetal calf serum, express HLA-DQ and DP on only small numbers of cells after treatment with the lymphokine. Thus, the conditions of culture, possibly the presence of a serum factor(s), influence the expression of class II antigens in normal keratinocytes. Furthermore, rIFN-gamma does not induce DP and DQ antigens readily in transformed squamous cells cultured in either serum-containing or serum-free medium.