Distribution of O-acetylated sialomucin in the normal and diseased gastrointestinal tract shown by a new monoclonal antibody

• Published in: Journal of clinical pathology Vol. 46; no. 4; pp. 323 - 329
• Main Authors: Milton, J D, Eccleston, D, Parker, N, Raouf, A, Cubbin, C, Hoffman, J, Hart, C A, Rhodes, J M
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and Association of Clinical Pathologists 01.04.1993; BMJ; BMJ Publishing Group LTD
• Subjects: Animals; Antibodies, Monoclonal - metabolism; Antibody Specificity; Biological and medical sciences; Colonic Neoplasms - chemistry; Digestive System - chemistry; Enzyme-Linked Immunosorbent Assay; Gastric Mucosa - pathology; Gastroenterology. Liver. Pancreas. Abdomen; Gastrointestinal Diseases - metabolism; Humans; Immunoenzyme Techniques; Medical sciences; Metaplasia - metabolism; Mice; Mice, Inbred BALB C; Mucins - analysis; Other diseases. Semiology; Sialomucins; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Human; Pathology; Stomach; Pathophysiology; Gut; Digestive diseases; Acetylation; Monoclonal antibody
• ISSN: 0021-9746; 1472-4146
• DOI: 10.1136/jcp.46.4.323

AIMS--To produce and characterise a monoclonal antibody specific for O-acetylated sialomucin and to assess its use in immunohistochemistry on a panel of normal and diseased intestinal tissue samples. METHODS--Mouse monoclonal antibodies were developed following immunisation with highly purified human colonic mucin. One of these (MMM-17) showed strong binding to mucin throughout the normal colon with relative lack of binding to colon cancer tissue. The binding epitope of MMM-17 was then characterised by screening for agglutination activity against a panel of human and animal erythrocytes and by assessment of its binding to a range of normal and chemically treated slot blotted mucins. Further immunohistochemical studies were then performed on formalin fixed, normal, and diseased human intestinal samples. RESULTS--Binding of MMM-17 to slot blotted human colonic mucin was reduced by 38 (SD 14%) (n = 4) by alkali treatment of the mucin, sequential alkali and sialidase treatment completely abolished binding. Sialidase treatment alone, however, caused only an 11 (11%) reduction in binding. MMM-17 failed to agglutinate any human, rabbit, rat or mouse erythrocytes. These findings were compatible with specificity of MMM-17 for sialomucins O-acetylated at the C-7 or C-8 positions on the sialic acid. Strong staining by MMM-17 was found in all goblet cells throughout all 40 normal colonic and rectal samples studied, but staining was absent in seven of 13 colorectal carcinomas. Normal duodenum (n = 16) and normal ileum (n = 3) all showed occasional positive goblet cells. The normal gastric antral mucosa was generally negative B MMM-17, but in all of 15 cases of gastritis with intestinal metaplasia the metaplastic glands were strongly positive for MMM-17. CONCLUSION--Monoclonal antibody MMM-17 has specificity for O-acetylated sialomucins and its binding depends both on the position of O-acetylation and on the adjacent oligosaccharide structure. Preliminary studies using the antibody on archival tissue samples support the previous reports of reduced O-acetylation in colon cancer demonstrated by indirect histochemistry and show the neo-formation of O-acetylated sialomucin in intestinal metaplasia in the stomach.