Characterization of the mucosal immune response in breast milk after peroral immunization of chimpanzees (Pantroglodytes) with Streptococcus mutans

The characteristics of the mucosal immune response to Streptococcus mutans cells, antigen A, antigen B, glucosyltransferases and glucan-binding protei ns were examined in four pregnant chimpanzees that had been immunized peror ally with Strep. mutans. Six pregnant chimpanzees served as non-immunized c ontrols. None of the chimpanzees harbored S. mutans. Samples of milk were c ollected from all animals throughout the experiment. Peroral immunization r esulted in an overall 17-fold median increase in SIgA in milk. Although SIg A1 comprised almost two-thirds of milk SIgA, Strep. mutans whole-cell antib ody activity was contained predominantly in the SIgA2 subclass. The differe nce between the specific activities of anti-Strep. mutans SIgA1 and SIgA2 a ntibodies compared over time reached the borderline of statistical signific ance (p = 0.08). The avidity of anti-Strep. mutans antibodies was low in th ree of four chimpanzees ana there was no evidence of affinity maturation. S IgA antibodies from the milk of all four immunized chimpanzees recognized a ntigen A. In three animals these antibodies were restricted to the SIgA1 su bclass and, in one animal, anti-a antibodies were confined to SIgA2. Antibo dies from all of the immunized chimpanzees recognized degradation products of antigen B in both the SIgA1 and the SIgA2 subclasses. Only two of four i mmunized chimpanzees responded to glucosyltransferases and these antibodies were restricted to the SIgA1 subclass. None of the chimpanzees responded t o the 74-kDa grucan-binding protein. However, three animals produced SIgA1 antibodies against the 59-kDa glucan-binding protein and two of these also produced SIgA2 antibodies against this protein. (C) 1999 Elsevier Science L td. All rights reserved.