4. Neonatal TA PMN contain lesser amounts of cellular BPI than adult peripheral blood PMN.
(A) BPI content of acid extracts of neonatal TA PMN (mean ± SEM of 46 ± 6 ng/106 PMN; n=8) and adult peripheral blood PMN (160 ± 54 ng/106 PMN; n=6) were determined by ELISA; (*) = p<0.05, unpaired t-test. (B) BPI-mediated killing activity of PMN acid extracts as measured by the concentration of PMN required to inhibit 90% of bacterial growth (IC90) was measured in vitro against the BPI-sensitive neonatal pathogen E. coli K1/r. Extracts of neonatal TA PMN had less antibacterial activity (mean ± SEM IC90=0.226% ± 0.050%, n=8) than extracts of adult PMN (IC90=0.070% ± 0.013%, n=6), (*) = p<0.05, unpaired t-test.