Figure 6

Antigen trapping and long-term retention. FDC-like cells (a, c) or macrophages (b, d), were pulsed for 30 min with HRPO/human IgG complexes. a, b, Cells were fixed after 4 days and double stained by a standard HRPO substrate reaction (brown) and for CD35 (red). a, In FDC-like cells antigen was present in its enzymatic active form, and CD35 was expressed. b, In macrophages only traces of antigen was detectable and CD35 is weakly positive. c, d, Cells were cultured for 16 days. In FDC-like cells (c) enzyme activity is still detectable, whereas in macrophages enzyme activity is absent.