AbstractThe present study was undertaken to determine whether monoclonal antibodies (moABs TKH‐2, MA54, MA61, B72.3, and CC49) directed toward O‐linked mucin‐type glycoprotein detect the NeuAcα2‐6GalNAc (sialyl Tn) epitope in meconium‐ and amniotic fluidderived mucin. Fetal colonic mucosal cells express the sialyl Tn antigen, particularly in goblet cell mucin. The reactivities of these moABs with a perchloric acid extract of meconium (meconium extract) and different native and neuraminidase treated glycoproteins were examined by solid‐phase enzyme‐linked immunosorbent assay (ELISA). All the moABs react with the meconium supernatant and meconium extract. The reactivities of TKH‐2, MA54, and MA61 are neuraminidase sensitive, and the reactivity of TKH‐2 with meconium extract was specifically inhibited by ovine submaxillary mucin (OSM). A NeuAcα 2‐6GalNAc epitope is the characteristic component in meconium. Mucin released from the fetal respiratory tract could, in part, provide an alternative source in the amniotic fluid. TKH‐2 is the most sensitive antibody directed to sialyl Tn antigen in meconium supernatant. The likelihood of TKH‐2 serving as the basis for a sensitive assay to detect sialyl Tn in meconium‐ and amniotic fluid‐derived mucin is pro