Immunohistochemical study of bovine lymph nodes with antibodies against S100 protein subunits: Comparison between lymph nodes of healthy and Mycobacterium paratuberculosis-infected cattle

Abstract Using immunohistochemistry, the differential distribution of the α subunit (S100α) and β subunit (S100β) of S100 protein was studied in mesenteric lymph nodes from normal or Mycobacterium paratuberculosis -infected cattle. In epithelioid cell granulomas, S100α-positive epithelioid cells and some giant cells were scattered among S100α-negative cells, which were predominant. The S100β-positive and -negative cells contained acid-fast bacilli. The presence of S100β-positive cells was not demonstrated in the granulomas. In normal component cells in the lymph nodes, follicular dendritic cells in the germinal centres and endothelium of lymphatic sinus and lymph vessels were positive for S100α. S100β was positive only in the endothelial cells of blood vessels. Results shown in the present paper are discussed in light of results obtained in other work on human tissues using the same sources of antibodies.