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. 2011 Mar 23;6(3):e17223. doi: 10.1371/journal.pone.0017223

Figure 4. Epifluorescence microscopy reveals that both human and mouse IgM enhance the binding and uptake of small particles by macrophages.

Figure 4

(A) Mouse macrophages incubated with human IgM-, human IgG-, BSA-, or DPBS-coated 1 µm beads show distinct fluorescence bead binding or internalization patterns. Left panel shows macrophages and their binding and uptake of beads coated with PBS, BSA (100 µg/ml), IgG (100 µg/ml) or dissociated IgG (100 µg/ml). Right panel shows the uptake of IgM (0–400 µg/ml) or dissociated IgM (100 µg/ml)-coated beads by representative macrophages. Coating of beads with increasing concentrations of IgM shows increasing fluorescence in the macrophages. Dissociating both IgG and IgM eliminates antibody-dependent uptake of these beads by macrophages. Numerical values denote the concentrations of IgM (µg/ml) used for coating the beads. (B) Macrophages phagocytose mouse IgG (100 µg/ml) and mouse IgM (100 µg/ml)-coated small beads (1 µm). Both human (A) and mouse (B) antibodies show similar effects. Scale bar is 10 µm.