C3 component deposition on exosomes. (A) Jurkat cells wherein apoptosis was induced were incubated with FCS and assessed for C3 deposition by flow cytometry. Tinted pattern indicates absence of primary antibodies. (B) Latex beads were coated with exosomes isolated after in vitro maturation or directly from the plasma of an anemic animal. The complexes were then analyzed by flow cytometry for the presence of IgM and C3 using the appropriate antibodies. Tinted patterns indicate absence of primary antibodies. (C) Plasma was collected from an anemic animal and ultracentrifuged to remove exosomes. Reticulocytes were matured in vitro for 48 hours in medium without (tinted pattern) or with plasma, heated-inactivated (–) or not (—). Exosomes were then isolated, coated on latex beads, and analyzed by flow cytometry for IgM or C3 component.