Abstract
ABSTRACT: The possibility that group B streptococci (GBS) may induce neonatal neutropenia by promoting neutrophil aggregation and the entrapment of aggregates in the lung was studied in vivo and in vitro utilizing a cell free GBS extract [(GBS)-trichloroacetic acid (TCA)]. The intravenous infusion of the extract into neonatal lambs induced reductions of circulating white blood cells (0 time, 3.1 × 103/mm3 ± 0.5 versus 2.2 × 103/mm3 ± 0.7) 5 min after infusion (p < 0.01). At necropsy these lambs had prominent accumulation of polymorphonuclear leukocytes in their pulmonary interstitium. Subsequently, neutrophil aggregation was studied by incubating GBS-TCA in human serum or phosphate-buffered saline with subsequent addition to human polymorphonuclear leukocytes in an aggregometer. GBS-TCA incubated in human serum induced prompt polymorphonuclear leukocyte aggregation (mean ΔT 12.3 % ± 2.8 in human serum versus ΔT 2.5% ± 2.1 in phosphate-buffered saline, p < 0.001). Preincubation of GBS-TCA followed by incubation in human serum with human GBS hyperimmune IgG significantly reduced aggregation (GBS-TCA in serum mean ΔT 14.9 ± 2.44 versus 5.42 ± 1.80, p = 0.002). Cell-free GBS products may induce polymorphonuclear leukocyte aggregation in the presence of whole serum. This pnenomenon might contribute to the pulmonary injury experienced by infants with GBS pneumonia and sepsis.
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Olson, T., Fischer, G., Hemming, V. et al. A Group B Streptococcal Extract Reduces Neutrophil Counts and Induces Neutrophil Aggregation. Pediatr Res 21, 326–330 (1987). https://doi.org/10.1203/00006450-198704000-00002
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DOI: https://doi.org/10.1203/00006450-198704000-00002