[Studies on the antitumor activity of human recombinant interferon alpha-2b in vitro]

Correlation between antiproliferative and binding activities of interferon (IFN) alpha-2b to various human cell lines was examined using human recombinant IFN alpha-2b. Burkitt's lymphoma Daudi cells and human renal cell carcinoma OS-RC-2 cells were sensitive to IFN alpha-2b, whereas two EB-virus-transformed B cell lines, FS and L-KT3, and human A375 melanoma cells showed low or no sensitivity. 125I-IFN alpha-2b binding assay revealed that the difference in IFN alpha-2b sensitivity was related to the number and the affinity of IFN alpha-2b receptors per cell. Experiments were then performed to investigate the influence of recombinant IFN alpha-2b on the cytostatic activity of monocytes against A375 cells in vitro. IFN alpha-2b enhanced the cytostatic activity of monocytes against A375 cells which showed low sensitivity to the direct growth inhibitory effect of IFN alpha-2b. Depletion of NK cells from the monocyte preparations by anti-Leu-11b monoclonal antibody and complement did not affect the monocyte activation by IFN alpha-2b, indicating that NK cells were not involved in this system.