MR is not essential for the phagocytosis of M avium 724. BMMϕs from WT or MR^–/– mice were infected with different ratios of complement opsonized (A-B) or nonopsonized (C-D) mycobacteria for 1 hour (A,C) or 4 hours (B,D). After infection, cells were washed, fixed, and stained with Auramine M. The percentage of phagocytic cells having ingested at least one mycobacterium was measured by fluorescence microscopy as described in “Materials and methods.” Values are expressed as means + SD. Data are representative of 3 separate experiments.