[Presence of antibodies in human colostral secretory IgA against enteric commensal bacteria: biological implications (author's transl)].

Antisecretory component, anti-alpha, anti-mu and anti-Fc (gamma) fluorescent antibodies were used to detect the presence of immunoglobulins with antibody activity against enteric commensal bacteria in human colostrum and serum. Forty nine colostrum samples were studied; all of them displayed secretory IgA (sIgA) antibodies reacting with Bacteroides thetaiotaomicron, Clostridium perfringens and Escherichia coli serotype O141:H32 without any K antigen. The amount of sIgA antibodies was always related to the sIgA colostral concentration varying greatly from one patient to another. For the 3 lactating women studied, the colostrum sIgA antibodies were largely predominant as compared to the antibodies of other classes; in their sera, no antibody having the same anticommensal specificity was detected in the IgA fraction while these antibodies were found in IgM and IgG. Our results are incompatible with the existence of local antigenic stimulation, and the IgA transfer from serum into mammary secretion appears unlikely, but these results are perfectly compatible with the antigenic stimulation of gut associated lymphoid tissue and subsequent migration in mammary tissue.