Location of PAP-positive cells in untreated animals compared with animals with recovery FDC networks. Spleens from untreated (a and b) and recovery animals (c and d) (8 mg/kg treatment followed by 3-month recovery) injected with PAP were stained with TSA-rhodamine (red) to visualize ICs and anti-IgD (green) to determine the location of PAP-positive cells. Representative spleens were examined by fluorescence microscopy and photographed at ×100.