Status of immunity of newborns against Yersinia enterocolitica: a preliminary report.

Out of 221 cord blood specimens assayed by whole cell agglutination for antibodies against Y. enterocolitica serogroup 0:3, 0:5,27, and 0:8, only four showed agglutinins despite the high percentage (33%) of agglutinating antibodies in 151 sera of pregnant women, ranging in titer from 4 to 32. Of 199 different cord sera tested, 25% to 28% showed low-level antibodies against erythrocytes treated with individual heat-extracts from Y. enterocolitica 0:3, 0:5,27, and 0:8. These sera equally agglutinated erythrocytes sensitized with the heat-extract of a randomly selected Escherichia coli strain. Conversely, when anti-yersinia hemagglutinins were absent in cord sera, concomitant cross-reactivity with E. coli was also absent. None of the 199 cord sera with a HA titer greater than or equal to 4 were reactive by whole cell agglutination. Under the test conditions used, CEA (common enterobacterial antigen) could be the main antigenic component to which the Y. enterocolitica hemagglutinins were directed. Nine of the reactive sera from pregnant women were treated with staphylococcal protein A with resultant loss of reactivity. Transplacentally acquired antibody directed primarily against the CEA antigen of Y. enterocolitica may protect the newborn against Y. enterocolitica infection.