S-Immunoglobulin A in human colostrum and milk: a longitudinal study in forty-eight nursing mothers.

: Human colostrum and milk collected at different times after the on-set of lactation (from 1st to 180th days) were tested for the levels of S-IgA. The technique of radial immunodiffusion with a anti-S.C. antiserum was employed. The highest percentage of S-IgA was found during the first five days post partum even if it rapidly declined during this time, thereafter remaining constant up to the 180th day of lactation. Absolute intake of S-IgA in infants during the first five days post partum was, in the same way, highest, but the amount of S-IgA intake remained high throughout the period of lactation ranging from 285 to 385 mg/die. On this basis it is suggested that breast-feeding is particularly important during the whole period of lactation and not only during its early stages.