FIGURE 3.

Association of human plasma-derived IgM/SIgM with S. flexneri. A, binding of IgM and SIgM to S. flexneri determined by ELISA. Bacteria coated in well plates were incubated with IgM or reconstituted SIgM at decreasing concentrations, with the 1:1 ratio corresponding to 0.61 μm of either Ab. Data are representative of two experiments performed in duplicates. B, LSCM pictures of immune complexes formed between bacteria and human plasma-derived IgM or SIgM. Bacteria constitutively expressing GFP are shown in green, whereas IgM and SIgM detected μ chain-specific and fluorescent Abs appear in red. Images are representative of one representative field obtained from 10 observations from two independent slides per experiment. Scale bars = 10 μm.