Antitumor activity of murine neutrophils demonstrated by cytometric analysis.

The cytostatic and cytolytic activities of activated polymorphonuclear neutrophils (PMNs) against YAC-1 lymphoma target cells were examined using multiparameter flow cytometric analysis. PMNs were resolved from tumor cells by 90 degrees light scatter. The number of surviving tumor cells was determined by adding a known concentration of fluorescent latex particles to the fixed cell suspension immediately prior to analysis and counting the particles simultaneously with the cells. Cell cycle progression of the YAC-1 target was studied by dual parameter analysis of DNA content and bromodeoxyuridine incorporation into tumor cell DNA either prior to or following addition of PMNs. The results indicate that activated PMNs effectively kill tumor cells within the first 24 h of coculture. However, between 24 and 48 h, tumor cells which escape destruction resume growth and eventually reach a growth rate greater than control cells.