Antigen handling in the spleen of the yellow-bellied toad, Bombina variegata.

The primitive anuran amphibian, the yellow-bellied toad, Bombina variegata, possesses the spleen with a large white pulp, containing the immune-complex-trapping-cells (ICTCs). The handling of immunologically different substances in the spleen of B. variegata was investigated. Adult toads were injected into dorsal lymph sacs with a mixture of rabbit peroxidase-antiperoxidase, FITC-Ficoll and latex beads. Two hours after injection antigens were found in the blood vessels of the spleen where some cells had also PAP on their surface. At that time antigens also reached the white and the red pulps. Finally PAP was trapped on the surface of ICTCs in the white pulp and was phagocytized by the white and red pulp macrophages. FITC-Ficoll was detected in the red pulp macrophages while latex beads in macrophages of both compartments. The present study suggests that ICTCs are specialized in trapping only immune complexes.