HUMAN COLOSTRUM IGA ANTIBODIES REACTING TO ENTEROPATHOGENIC ESCHERICHIA-COLI ANTIGENS AND THEIR PERSISTENCE IN THE FECES OF A BREAST-FED INFANT

IgA antibodies reacting to enteropathogenic Escherichia coli (EPEC) an tigens in human colostrum and their role in the inhibition of EBEC adh erence to HEp-2 cells were studied, Colostrum IgA was isolated with a Sepharose anti-IgA column. IgA-depleted colostrum lost its inhibitory effect on EPEC adhesion, while the IgA-enriched eluate was a potent ad herence inhibitor, The same eluate showed a significant loss of inhibi tory activity after absorption with an EPEC strain showing localised a dherence (LA+), but no alteration after absorption with an LA-strain. No bands were observed in Western blot analysis with LA+ absorbed elua te and with a crude extract of the EPEC strain, but;the eluate;absorbe d with LA-showed a strong recognition of a 94-kDa band, a molecular we ight equivalent to that of intimin. Colostrum antibodies reacting to n on-protein antigens were not detected by Western blot analysis, The pe rsistence of anti-EPEC IgA in the gastrointestinal tract was shown by the strong reactivity to the 94-kDa band in Western blot analysis of o ne mother's colostrum and her infant's faeces, These data confirm the role of colostrum antibodies in protecting the neonate against infecti ons due to EPEC.