Immunoglobulin A and secretory immunoglobulin A antibodies to purified type 1 Klebsiella pneumoniae pili in human colostrum.

Immunoglobulin A antibodies with binding specificity for purified Klebsiella pneumoniae type 1 pili were detected by an enzyme-linked immunosorbent assay in 20 of 21 human samples (95%). The concentrations of secretory immunoglobulin A antibody in colostrum directed against the pili were calculated by comparison of experimental enzyme-linked immunosorbent assay values with values obtained from known secretory immunoglobulin A concentrations. The presence of antibodies to K. pneumoniae type 1 pili was confirmed by double diffusion-gel studies with selected specimens of colostrum. This study shows that in the majority of human colostral samples examined, secretory immunoglobulin A antibodies with specificity for K. pneumoniae type 1 pili can be commonly found in variable, but frequently high, concentrations.