The phagocytosis capacity assay: a new radiometric phagocytosis test for clinical use.

A radiometric technique is described for measuring phagocytosis which does not require separation of extra- and intracellular microorganisms. Following phagocytosis of optimally opsonized yeast cells (Saccharomyces cerevisiae) by mononuclear cells (MNC) or granulocytes, yeast cells remaining extracellular are labeled with [75Se]L-selenomethionine. To measure the phagocytic capacity of the cell population investigated, 1-4 x 10(6) leukocytes are incubated with 5, 10, 20, 30 and 40 x 10(6) yeast cells/ml for testing. Depending on the actual number of phagocytes in the cell populations investigated, different optimal yeast cell concentrations may be determined. Provided measurements are carried out at these optima even moderate effects of therapy can be detected. In a preliminary study of 22 patients with Hodgkin's disease it was shown, that the phagocytic activity of the MNC fraction was higher, but the activity of granulocytes lower, than that of the healthy controls. After combined chemotherapy the above mentioned values returned to normal. This simple, exact method is recommended for clinical use.