Variation in the amount of T antigen and N-acetyllactosamine oligosaccharides in human cervical mucus secretions with the menstrual cycle

It has been hypothesized that the carbohydrate portion of mucins present in the endocervical canal plays an important role in conferring specific physicochemical properties (e.g. viscosity and hydration) to the mucus gel through the menstrual cycle. Our recent finding showing an increase in the amount of MUC5B mucin protein at midcycle has raised the question of whether the mucin O-glycan content also varies to confer specific hydrodynamic properties to secreted mucins during ovulation. Using lectins as carbohydrate probes, we have identified two common mucin oligosaccharide structures, T antigen and N-acetyllactosamine, within secretory granules in human endocervical glands during the proliferative phase of the menstrual cycle. Analysis of endocervical secretions by enzyme-linked lectin assay revealed that the amounts of T antigen and N-acetyllactosamine are maximal at midcycle. Lectin blot assay of immunoprecipitated MUC5B demonstrated that the mucin is a carrier of the T antigen and N-acetyllactosamine oligosaccharides in cervical mucus secretions. The amounts of T antigen and N-acetyllactosamine oligosaccharides on MUC5B increased during the first half of the cycle, peaked at midcycle, and dramatically dropped at the end of the cycle. The peak in MUC5B mucin protein and carbohydrate content coincides with the change in mucus character that occurs at midcycle. The role of O-glycans on mucins may be to hold water within the endocervical canal during ovulation to facilitate sperm migration.