[Validity limits of data on secretory IgA].

Secretory IgA (sIgA) in saliva, and sometimes in expectoration, have been titrated in various groups of persons, both in pediatric age and in adults, by means of radial immunodiffusion technic. The aim was to find differences among sIgA levels in the course of respiratory tract infections, both acute and chronic, in consequence of treatment with Erythromycin (in children and in adults) in consequence of surgical intervention (in adults). Adjunctive aim was to establish if it was possible to recognize hereditary of the character that remark the predisposition to produce high sIgA quantities.