Human IgG, but not IgM, drastically enhances uptake of large beads by macrophages.

<p>(A) Macrophages effectively bind and internalize IgG-coated, but not IgM-, BSA-, or PBS-coated, large beads (∼8.31 µm; p<0.05). (B) Counting numbers of “beads/cell” shows that IgG-coated beads are taken up in greater quantities. Only a small number of cells binds or internalize IgM-coated beads. Bead uptake saturates at 100–500 µg/ml IgG-coating concentrations. Percentage values for each IgG and IgM condition will add up to the corresponding values shown in panel A. (C) Differential interference contrast (DIC) images show examples of IgG-coated 8.31 µm large beads that associate with or are engulfed by macrophages. A similar effect was not seen with IgM-, or BSA- or PBS-coated beads. Scale bar is 10 µm.