Presence of H Type 3/4 chains of ABO histo-blood group system in serous cells of human submandibular gland and regulation of their expression by the secretor gene (FUT2)

We have investigated by immunochemistry the distribution of H Type 3/4 chai ns of the ABO histo-blood group system in human submandibular gland using a monoclonal anti-H MBr1 antibody specific for H Type 3/4 chains, and have f ound the expression of H Type 3/4 chains was mainly in the serous cells. Se rous cells from secretors were stained by MBr1 but not by anti-A and anti-B antibodies, whereas serous cells from nonsecretors exhibited a negative re action with MBr1. Mucous cells were not stained by MBr1. Only a few striate d duct cells showed a weak reaction with anti-H MBr1. These results suggest ed that the H Type 3/4 chains were distributed predominantly in the serous cells of the human submandibular gland and that secretor Type alpha(1,2)fuc osyltransferase (Se enzyme) controlled the synthesis of H Type 3/4 chains i n vivo. Saliva also contained H Type 3/4 chains, which were controlled by t he secretor gene (FUT2). The differences in the distributions of H Type 1, H Type 2, and H Type 3/4 chains of the ABO histo blood group system in the submandibular gland are discussed.