1El-Khashaab TH, 2Atef AA, 3Francis WM and 3Motawea MS.
1Immunology & Microbiology Department, Faculty of Medicine, Ain Shams University, 2Biochemistry Department, Faculty of Science, Ain Shams University and 3U.S. Naval Medical Research Unit No. 3, Cairo, Egypt.
A prospective study to assess whether maternal milk IgA antibodies (Abs) against E.coli heat labile-toxin (LT) and colonization factors (CFs) can protect breast-fed children against diarrhea was carried out in Abo Homos, Behira, Egypt. This study includes 118 breast feeding women and their children. An ELISA test was developed to detect specific IgA Abs in breast milk against Enterotoxigenic E.coli (ETEC) colonization factor /I (CFA/I) and LT. Rectal swabs (n=118) were taken from children besides reporting diarrhea, if present. Specific IgA antibody against ETEC CFs antigens; CFA/I, coli surface1 (CS1), CS2 and CS3 and CS6 `were detectable in 98% to 100% of the tested milk. The correlation coefficient between sIgA titers against CS1 and CS2 was the highest, r =0.85, P<0.001. Secretory IgA against CS3 at Ab titer >50 showed the lowest ETEC diarrheal occurrence rate with a relative risk of 0.3, P< 0.11. Low range titer 1-9 of maternal milk Ab against CS3 and CS6 also provide some protection for children in the study from infection with ETEC strains. Expression of LT and CS3 phenotypes were significantly associated with the occurrence rate of symptomatic infection (GMT=13 for 24 children and GMT=51 for 18 children) and asymptomatic infection (GMT=15 for 21 children and GMT=194 for 3 children) by LT and CS3 , respectively. No statistical correlation between milk antibody titers against LT, CS3, and CS6 antigens and disease severity (defined as excess stool water greater than 10mg /kg/day in infants with loss of electrolyte during less than 14 days) was recorded.