A Method to Evaluate the Capacity of Monocytes and Macrophages to Inhibit Multiplication of an Intracellular Pathogen

A new method to assess intracellular inhibition of multiplication or killing by normal and activated mouse peritoneal macrophages, human peripheral blood monocytes, and human monocyte-derived macrophages is described. This method involves measurement of incorporation of [3H]uracil into nucleic acids of the obligate intracellular parasite Toxoplasma gondii. The method utilizes the observation by Pfefferkorn and Pfefferkorn (1977) that [3H]uracil is incorporated in substantially greater amounts by T. gondii than by certain mammalian cell types. Differential uptake of [3H]uracil by Toxoplasma-infected and uninfected cultures allows for evaluation of the ability of macrophages or monocytes to inhibit or kill this organism. This method has been adapted to microsystem.