HELICOBACTER-PYLORI ACQUISITION IN INFANCY AFTER DECLINE OF MATERNAL PASSIVE-IMMUNITY

We evaluated the natural history of Helicobacter pylori infection and the host immune response in 80 infants, and determined seroprevalence of H. pylori infection in their Taiwanese mothers. Decline in passivel y transferred maternal anti-H. pylori IgG antibodies and subsequent H. pylori infection was assessed in infants over 14 mo. A sensitive and specific, 96-well microtiter ELISA for the detection of H. pylori IgG antibodies was used to evaluate maternal serum (single specimen) and t heir infants (birth, 1, 2, 3, 6, 12, and 14 mo). Sera were also evalua ted by ELISA for the presence of anti-H. pylori IgM antibodies in the infants. Maternal H. pylori IgG seroprevalence was 62.5% [50/80; 95% c onfidence intervals (CI), 51-73%]. All infants born to the 50 seroposi tive mothers passively acquired maternal H. pylori IgG. Transplacental ly transferred maternal anti-H. pylori IgG lasted until about the 3rd mo of life, and disappeared in nearly ail the infants by 6 mo of age. Seven and one-half percent of infants (6/80; 95% CI, 3-16%) acquired H . pylori infection; two were born to H. pylori-negative mothers. Among the six IgG seropositive infants, an IgM response specific for H. pyl ori antigens was detected and appeared to precede the rise in IgG in f ive. We conclude that maternal passive transfer of IgG antibodies occu rs in the infant and disappears by 6 mo of age. H. pylori infection is acquired in infancy in this population: IgM antibodies against H. pyl ori are detectable, seem short-lived, and appear to precede IgG antibo dy development.