Transfer of the IL-6 gene into a human colorectal carcinoma cell line and consequent enhancement of tumor antigen expression.

cDNA encoding the human IL gene (580 bp), inserted into a retroviral expression vector carrying neomycin resistance selective marker, was introduced into HT-29 human colon carcinoma cells by lipofection. Interleukin-6 activity was measured by ELISA and bioassay using B9 cells. Interleukin-6 secreted by transfected HT-29 cells was shown to be biologically active. The expression of the human tumor associated antigen CEA (carcinoembryonic antigen), HLA classes I and II, and ICAM-1 antigens in the transfected HT-29 cells were also analyzed by flow cytometry. Significant enhancement in the expression of CEA but not in the expression of HLA class I, HLA class II and ICAM-1 antigens, was observed in the transfected HT-29 cells as compared to the parental HT-29 cells. These results provide experimental evidence that enhancement of tumor antigen expression on tumor cells can be induced by IL-6 gene transfection, and suggest another potential role for the use of IL-6 gene transfer in the immunotherapy of human cancers.