RESUMEN
We have examined the immunohistochemical distribution of H Type 1 and of H Type 2 substances of the ABO blood group system in human submandibular gland using either of the two anti-H monoclonal antibodies MAb 1E3 and MAb 3A5. MAb 3A5 was specific for H Type 2, and MAb 1E3 reacted with each of H Type 1-H Type 4 artificial antigens. We have developed a competitive inhibition method against H Type 2 and have obtained MAb 1E3, which is fairly specific for H Type 1 under certain conditions. Mucous cells from secretors were strongly stained by 1E3 and weakly by 3A5, whereas those from nonsecretors showed no reaction with 1E3 and 3A5. Serous cells from both secretors and nonsecretors were stained neither by 1E3 nor by 3A5. Striated and interlobular duct cells were strongly stained by 1E3 and by 3A5, regardless of the secretor status. These results indicated that the expressions of the H Type 1 and H Type 2 in different cell types of the submandibular gland were controlled by different genes. In addition, we have determined the acceptor specificity of two alpha(1,2)fucosyltransferases (H and Se enzymes) after transient expressions of the FUT1 and FUT2 in COS7 cells, and found that the H enzyme activity was similar for both Type 1 and Type 2 precursors, and that Se enzyme activity with the Type 1 precursor was higher than that with the Type 2 precursor. Expression of the H Type 1 antigen in mucous cells was found to be dependent on the Se gene, whereas expressions of the H Type 1 and H Type 2 antigens in striated and interlobular duct cells were dependent on the H gene. (J Histochem Cytochem 46:69-76, 1998)