A rapid spectrophotometric method for assessing macrophage phagocytic activity

The method described provides a rapid and inexpensive in vitro assay of phagocytosis by mononuclear phagocytes. This assay utilizes yeast cells, stained with congo red, as the target particle and quantitation is performed spectrophotometrically. An attractive feature of this assay is that phagocytic activity is assessed using large sample sizes, in this case approximately 1 X 10(6) macrophages per sample, resulting in a more accurate evaluation of phagocytosis than assays dependent on microscopic quantitation.