THE EFFECT OF INTERFERON-GAMMA AND TUMOR-NECROSIS-FACTOR-ALPHA ON THEEXPRESSION OF ICAM-1 AND HLA-DR MOLECULES ON CELLS OF A HUMAN GERM-CELL NEOPLASM AND THEIR SUSCEPTIBILITY TO LYSIS BY LYMPHOKINE-ACTIVATED KILLER-CELLS

The ICAM-1 molecule plays a role in the interaction of NK cells with a variety of tumor cells, including carcinoma, melanoma and glioblastom a cells. In the present study, we analyzed the effect of IFN-gamma and TNF-alpha on both the expression of HLA-DR and ICAM-1 molecules on HG CN (Germa-2), and on their susceptibility to lysis by LAK cells. Our r esults show that 1,000 U/ml IFN-gamma induced a substantial increase i n the expression of both ICAM-1 molecules and HLA-DR on the cell surfa ce, while the effect of TNF-alpha on the expression of these molecules was substantially less prominent. When Germa-2 cells, previously expo sed to 1,000 U/ml IFN-gamma, were employed as target cells in a 4-hour Cr-51 release assay, a statistically significant increase in the lysi s by LAK cells was noted. These results show that in the presence of I FN-gamma, Germa-2 tumor cells undergo modulation which affects both th e expression of ICAM-1 and HLA-DR molecules as well as their susceptib ility to lysis by LAK cells.