Relationship of human natural lymphocyte‐mediated cytotoxicity to cytotoxicity of breast‐cancer‐derived target cells

Mononuclear cells from 115 individuals were tested in a 4‐h chromium release assay against two breast‐cancer‐derived cell lines, G11 and MCF‐7, and a myeloid line, K‐562, shown previously to be sensitive to natural cytotoxicity. These data were analyzed in a manner designed to detect hyperreactivity against the breast cell lines relative to the level of reactivity against K‐562. A high proportion of breast cancer patients were found to be relatively hyperreactive against G11 (12/18 or 67%) and against MCF‐7 (10/18 or 56%). Fibroadenoma patients were very similar to the normal females, with 0/11 hyperreactive to G11 and 1/11 (9%) to MCF‐7. However, several normal males (7/17 or 41%) were hyperreactive to G11 but not to MCF‐7 (2/17 or 12%). Colon cancer and lung cancer patients were also more hyperreactive to G11, 4/8 or 50% and 4/6 or 67%, respectively, than they were to MCF‐7, 1/8 or 13% and 1/6 or 17%, respectively. Only fibrocystic patients resembled the breast cancer patients, with some but not as many individuals being hyperreactive to G11 (3/8 or 38%) and to MCF‐7 (2/8 or 25%). With another group of individuals reproducibility of the method was demonstrated, with only 1/14 or 7% of normal females and 12/17 or 70% of breast cancer patients being hyperreactive to G11. Thus, natural cytotoxicity toward K‐562 can be related to breast cancer‐associated cytotoxicity toward MCF‐7 in a way that distinguishes a majority of brest cancer patients specifically from other groups of individuals.