Immunohistochemical detection of S-100 in the spleen of the Philippine swamp buffalo (Bubalus bubalis carabanensis Castillo, 1998) (Artiodactyla: Bovidae)

The localization of S-100 protein in the spleen of Philippine swamp buffalo was demonstrated by immuno-staining of 14 spleen sections from seven male and seven female 2-year-old Philippine swamp buffaloes. It has been observed that this substance was present in the nerve elements, and in the endothelial cells lining the capsular arteries, trabecular arteries, penicillar arterioles and sheathed capillaries in the red pulp, and splenic arterioles in the white pulp, as well as in the macrophages and reticular cells that formed a sleeve around the penicillar arterioles and sheathed capillaries of the spleen. S-100 was absent in the lymphoid follicles and PALS of the white pulp. The localization of S-100 in the endothelial cells of sheathed capillaries is suggestive of its function in regulating the semi-permeability of the blood vessels while the demonstration of S-100 in the nerves may indicate that it is transported from gliocytes secreting it to the target cells. Absence of S-100-immunoreactive dendritic cells in the white pulp of the Philippine swamp buffalo suggests that they are not present in normal tissues and may be used as a marker of immunity. The present observations are basically similar to those in the bovine and sheep spleens except for some differences mentioned earlier