[Phagocytic and intracellular killing activity of rat macrophages: critical analysis of 2 different evaluation...

Two different evaluation methods of the "in vitro" bacterial killing activity of macrophages were compared; the former based on the determination of the number of viable microorganisms in the supernatant of macrophage cultures by a microbiological plate method; the latter based on the evidentiation of intracellular killing by differential staining of living and killed microorganisms with acridine orange. Phagocytic and microbicidal activities of peritoneal cells were investigated by the two methods in control rats and in tumor-bearing rats. Qualitative and quantitative differences in the kinetics of phagocytosis and microbial killing were evidentiated in macrophages from tumor-bearing rats. Furthermore, both methods proved to be suitable and reproducible.