Neonatal group B streptococcal sepsis is characterized by cardio-pulmonary failure, leukopenia and pulmonary leukostasis. The aim of this study was to evaluate the role of granulocytes (G) in the response to infusion of group B Type III streptococcal exotoxin. Five lambs, age 1-4 weeks, were studied awake in a whole-body, pressure-compensated, integrated-flow plethysmograph before and after neutrophil depletion with hydroxyurea. A two phase reaction to the toxin was observed. During the first phase, which lasted about 30 minutes, circulating G decreased, pulmonary arterial (PA) pressure, temperature and lung lymph flow increased. At the same time a 50% reduction in dynamic lung compliance (Cdyn) and a 300% increase in lung resistance (R1) was observed. Thoracic gas volume (TGV) was unchanged. In the second phase 3-5 h. after toxin, PA pressure and temperature remained slightly elevated, circulating G increased and lung lymph protein clearance (LPC) was doubled. In this phase R1, was moderately increased, but Cdyn and TGV were unaffected. After G depletion, GBS toxin infusion resulted in a significantly reduced increase in R1 (60%) in both phases and significantly less decrease in Cdyn (10%) in Phase I. PA pressure response was unchanged, whereas the increase in LPC was less marked. The results indicate that G contribute to, but are not the sole mediators, of altered lung mechanics and increased permeability of pulmonary exchange vessels seen after GBS toxin administration; whereas pulmonary hypertension does not appear to be mediated by G.
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Sandberg, K., Engelhardt, B., Bratton, D. et al. 1825 THE ROLE OF GRANULOCYTES IN THE LUNG FUNCTION RESPONSE TO GROUP B STREPTOCOCCAL TOXIN IN YOUNG LAMBS. Pediatr Res 19, 415 (1985). https://doi.org/10.1203/00006450-198504000-01843