A comparative study on S-100 protein-immunoreactive cells in lymph nodes.

S-100 protein-immunoreactive cells of the lymph node were examined in the duck and 9 mammalian species, such as guinea pigs, dogs, cats, horses, pigs, goats, cows, Japanese serows and crab-eating monkeys. S-100 protein was detected in follicular dendritic cells (FDC) and tangible-body macrophages (TBM), sinus and parenchymal macrophage (MP), sinus endothelial cells (SEC) and interdigitating reticulum-like cells (IRC) in the node of mammalian species, but not in the duck except nervous elements. S-100-positive FDC and TBM were detected in germinal centers of the nodes in all mammalian species, but immunoreactivity of the other 3 cell types varied according to animal species and individuals of the same species. S-100 alpha subunit was detected in FDC, with the exception of those of the duck and guinea pig. The subunit was also detected in SEC of the dog, cow and Japanese serow. In the guinea pig, a unique S-100 alpha-positive giant dendritic cell (GDC) was found in the subsinusal cortical area. In addition, S-100 immunoreactive lymphocytes were observed in the paracortex-equivalent area of pig nodes. Arterial endothelial cells of the pig and cow were immunoreactive to S-100 beta subunit.