Impaired Chemotaxigenesis by Type III Group B Streptococci in Neonatal Sera: Relationship to Diminished Concentration of Specific Anticapsular Antibody and Abnormalities of Serum Complement

摘要

Summary: A chemotaxigenesis (CTG) assay employing adult or neonatal sera, type III group B streptococci (GBS) and polymorphonuclear leukocytes (PMNs) was designed to evaluate the role of PMN mobilization in the pathogenesis of type III GBS infection in neonates. Generation of C5a in healthy adult sera with moderate-high (3–40 μg/ml) or low (≤2 μg/ml) levels of specific anticapsular antibody was confirmed by PMN aggregometry and by the neutralization of CTG by goat anti-human C5. CTG was significantly (P P P both complement and specific IgG to low antibody-containing neonatal sera was required to enhance their CTG activity to high antibody adult values. CTG by type III GBS in neonatal sera-neonatal PMN mixtures was only 25% (high antibody sera) and 14% (low antibody sera) of values for paired maternal sera mixtures reacted with adult PMNs (P < 0.001). These studies demonstrate that CTG by type III GBS in neonatal sera is markedly diminished and that low concentrations of specific anticapsular antibody and abnormalities of complement function contribute to impaired PMN mobilization in human neonates.