INTESTINAL IMMUNE-RESPONSE OF VOLUNTEERS INGESTING A STRAIN OF ENTEROADHERENT (HEP-2 CELL-ADHERENT) ESCHERICHIA-COLI

Enteroadherent Escherichia coli (EAEC) strains identified by adherence to HEp-2 tissue culture cells have been incriminated epidemiologicall y as important etiologic agents of diarrheal disease in both adult tra velers and children in developing countries, One strain, JM 221, with no recognized E. coli virulence characteristics other than adherence t o HEp-2 cells, caused diarrhea in 5 of 16 volunteers ingesting it, We studied the secretory immunoglobulin A (sIgA) responses to EAEC JM 221 of five volunteers,vith diarrhea and five volunteers who remained hea lthy after challenge. sIgA was extracted from stools obtained prechall enge and 7 days postchallenge. Total sIgA was standardized for all spe cimens, Specific sIgA titers were determined by dot blotting with the following JM 221 antigens: water-extractable surface antigens, whole c ells, lipopolysaccharides, and outer membrane proteins, All five subje cts who became ill had fourfold or greater rises in titers against eac h of the four antigens, The five subjects who remained healthy followi ng challenge did not exhibit significant rises in titers to any JM 221 antigens, but their mean titers were significantly higher than the me an prechallenge titers of the volunteers with diarrhea, suggesting tha t high intestinal sIgA titers may be protective. The significant incre ases in intestinal antibody against JM 221 in the subjects who became ill is further evidence of the enteropathogenicity of EAEC strains.