Effects of uninfected erythrocytes on the phagocytosis of iRBCs and latex beads by adherent cells. PBMCs (10⁶/mL) were allowed to adhere to chamber-well slides. Nonadherent cells were washed off, and the remaining adherent fraction was subsequently incubated in duplicates for 2 or 18 hours (3 donors each) with 5 × 10⁵/mL iRBCs, PfSL (not shown), GM, or equivalent numbers of 2.8-μm latex beads, in the presence or absence of 1:10 diluted uninfected erythrocytes, Giemsa stained, and visualized by light microscopy. Representative images are shown of adherent monocytes (A) and their reduced numbers following addition of uninfected erythrocytes (B) (magnification, × 100 for both panels), phagocytosis of iRBCs by adherent monocytes in the absence (C) or presence (D) of uninfected erythrocytes, and phagocytosis of latex beads by adherent monocytes in the absence (E) or presence (F) of uninfected erythrocytes (magnification, × 1300; oil immersion for panels C-F). Arrows indicate iRBCs or latex beads.