Recruitment of OKM1 staining lymphocytes with selective binding to K-562 tumour targets by interferon
Salata, R.A.; Schacter, B.Z.; Ellner, J.J.
Clinical and Experimental Immunology 52(1): 185-190
1983
ISSN/ISBN: 0009-9104 PMID: 6190593 Document Number: 217368
Spontaneous cytotoxicity of human lymphocytes for tumors is increased by interferon (IFN) without change in the overall fraction of cells binding to targets. An indirect immunofluorescent technique was developed to stain lymphocytes conjugated to human leukemia K-562 tumor cells in agarose with monoclonal antibodies. This allowed assessment of lymphocyte subpopulations binding to tumor cells without disruption of conjugates. Overall binding of nonadherent (NA) lymphocytes to tumor targets following incubation at 37.degree. C for 6 h was 13.3 .+-. 0.3% compared to 12.5 .+-. 0.7% with inclusion of IFN at 100 .mu./ml. When NA lymphocytes were incubated with K-562 tumor cells without IFN, OKM1 and OKT3 staining lymphocytes comprised 16.8 .+-. 3.5% and 83.0 .+-. 1.3% of the total lymphocyte population and 32.5 .+-. 1.3% and 70.2 .+-. 2.6% of lymphocytes conjugated to tumors. Incubation with IFN significantly increased OKM1 staining cells in the total NA population to 57.2 .+-. 5.6% (P < 0.01) and within tumor conjugates to 59.2 .+-. 2.7% (P < 0.01), while OKT3 staining cells decreased to 58.3 .+-. 5.2% (P < 0.02) and 45.3 .+-. 1.2% (P < 0.001), respectively. IFN increased cytotoxicity of NA cells for 51Cr-labeled K-562 by 66% at an effector to target ratio of 30:1 (P < 0.001). OKM1 staining cells bind more avidly to tumor targets in the absence of IFN. IFN selectively increases the proportion of OKM1 staining lymphocytes with a concomitant increase in their binding to tumor cells. Enhancement of cytotoxicity by IFN in the NK system may result, in part, from conversion of OKT3 to OKM1 staining cells which are more efficient killers.