Further studies on the effect of human effusions on the mitotic index of mammalian cells grown in cell culture.

Employing L and HeLa cells grown as a monolayer on coverslips in Leighton tubes, 19 human effusions were screened for the presence of growth-promoting factors. The screening test consisted in recording from microscopic studies the percentage of cells in division after incubation for 36 hours in the test medium, with the last 12 hours of incubation in the presence of a mitostatic agent. The effusions were diluted to one-third strength with Hanks' balanced salt solution and were tested in triplicate; a minimum of 500 cells were counted for each replicate. All effusions possessed growth-promoting activity. The results suggested that effusions from patients with malignant disease do not differ in growth-promoting activity in cell culture from effusions obtained from patients with non-malignant disorders.