Antibodies against invasion plasmid coded antigens of shigellae in human colostrum and milk.

Colostral and milk samples of Swedish, Vietnamese and Costa Rican mothers living under various socioeconomic conditions were tested for the presence of shigella invasion plasmid coded antigen (Ipa) specific antibodies. IgA antibodies of this specificity were found in significantly higher titres in samples of Vietnamese (600 +/- 338) than in samples of Swedish or high income Costa Rican mothers (190 +/- 224 and 290 +/- 241, respectively; p < 0.05). Specific IgA titres in the low income group of Costa Rican mothers (470 +/- 338) did not differ significantly from the values obtained in Vietnam. While no Ipa specific IgM could be detected in any of the samples tested, specific IgG was found in 90% of the Vietnamese colostrum. These data indicate that antibodies which could be responsible for the dysentery-preventing effect of breast feeding are indeed present in human colostrum and milk in areas where shigellosis occurs with relatively high incidence.