Tissue localization of conglutinin, a bovine C-type lectin

The distribution of bovine conglutinin (BK) in sections of frozen bovine tissues was studied by the indirect immunoperoxidase technique using a monospecific rabbit anti-BK antibody. BK was found in the cytoplasma of all hepatocytes, indicating that the liver is a major site of synthesis of BK. In the germinal centres of the spleen, tonsils and lymph nodes the anti-BK staining was restricted to a population of cells with a distribution and morphology characteristic of follicular dendritic cells. Macrophages in lung and thymus, and glia cells in cerebrum, revealed a granular staining reaction within the cytoplasma. Endothelial cells of blood vessels reacted with anti-BK. The intensity of this reaction varied greatly between the organs, the most pronounced reaction being seen in the glomeruli of the kidney, and in the capillary sinusoides of the cortex of the adrenal gland. The high endothelial venules of lymph nodes and tonsils were also stained. These findings suggest that BK, which until now has been described only as a circulating molecule, may exhibit a biological function within the BK-positive tissues.