Increased Natural Killer Cells in Fluids. A New, Sensitive Means of Detecting Carcinoma

Objective: Natural killer (NK) cells are cells of undefined lineage that are capable of lysing certain tumor cell lines in vitro. Determination of NK cell percent (NK%) in effusions by flow cytometry could aid in the detection of malignancies.

Study Design: Over a six-month period at the Houston Veterans Affairs Medical Center, fresh effusions were routinely processed for cytology, and a portion was submitted for lymphocyte immunophenotyping using the FACScan and a panel including CD16/CD56 for NK cells. Seventy fluids (42 pleural, 28 peritoneal) from 62 men were examined.

Results: NK cell percents were markedly increased in 15 cases (29-68%, mean 45.5) and low in 55 (2-20%, mean 8). Fourteen of the 15 cases with increased NK% were positive for carcinoma (93%), while 54/55 cases with low ones were negative for carcinoma (98%). Mesotheliomas, lymphomas and leukemias had low NK%.

Conclusion: Using the Mann-Whitney U test, an increase in NK% predicts metastatic carcinoma with a P level of < .00001.