An IgM-class monoclonal antibody that reacts specifically with the mucoglycoprotein produced by human gastric epithelioglandular mucous cells. It is possible to stain specifically human gastric epithelioglandular mucous cells and the mucus secreted by the cells by conducting immunological tissue staining with a labeled derivative of the above antibody. Further it is possible to use the antibody for analyzing mucoglycoproteins originating in the gastric epithelioglandular mucous cells contained in the human body fluid and for examining or diagnosing cancer.
