HLA-DR expression in a human colonic carcinoma cell line.

A human colonic carcinoma cell line (HCA-7) isolated from a well differentiated mucoid adenocarcinoma of the colon has been maintained in vitro for 3 years. It spontaneously synthesizes HLA-DR which is mainly intracytoplasmic. Stimulation with lymphocyte conditioned medium and recombinant gamma-interferon results in enhanced synthesis of HLA-DR and the appearance of the antigen on the cell surface. A dose response study showed that maximal stimulation of the culture was achieved with 50 units/ml of recombinant gamma-interferon. Staining for HLA-DR was uneven being confined to focal areas of the monolayer, which is similar to the focal expression of HLA-DR seen in sections of adenocarcinoma of the colon. The functional significance of this phenomenon is unclear, but it may explain the presence of lymphoid infiltrates in tumours.