A monoclonal antibody against hamster tracheal mucin, which recognizes N-acetyl-galactosamine containing carbohydrate chains as an epitope

Airway mucin that is present in airway secretion, plays an important role i n host-defense by trapping airborne particles and removing them by mucocili ary transport system. For the study of mucin, it is crucially important to have antibodies specific against mucin because other commonly used methods such as histologic stain for the detection of mucin usually suffer from var ying levels of nonspecificity, In this study, we produced a monoclonal anti body (MAb) against hamster airway mucin, which is one of the most commonly used animal species for the study of mucin in vitro, and characterized its immunological properties along with the determination of the epitope it rec ognizes, The MAb, which was named MAb HTA, was IgM isotype and specific aga inst mucin from both in vitro cell culture and in vivo airway secretion. In Western blot, MAb HTA specifically recognized high molecular weight airway mucin, which was also confirmed by the appearance of peak profile of immun ological signal only on void volume fraction in Sepharose CL-4B gel filtrat ion chromatography, It also immunoprecipitated high molecular weight hamste r airway mucin with the aid of anti-mouse IgM agarose, In immunohistochemic al stain of hamster trachea, it showed strong signal on airway epithelium a nd also on the mucin secreting goblet cell granules. The immunological sign al was greatly increased by the treatment of endotoxin, which has been repo rted to cause airway secretory cell metaplasia. The MAb HTA recognized carb ohydrate chains containing N-acetyl-galactosamine, one of the linking sugar s of airway mucin, as an epitope, Treatment of mucin with N-acetyl-galactos aminidase caused great reduction of immunological signal. To the best of ou r knowledge, this is the first to report a MAb that recognizes N-acetyl-gal actosamine, a linking sugar of airway mucin, The specificity of MAb HTA aga inst airway mucin and the clear demonstration of the epitope it recognizes should greatly aid the pharmacological and biochemical study of mucin in va rious physiological and pathological situations.