Abstract
Defects in the AP of complement are thought to play a role in the susceptibility of newborns (NB) to infection. The CL assay was used to measure the ability of varying quantities of 20 cord sera to opsonize zymosan (Z). Concentrations of AP components were correlated with CL and outcome. Luminol enhanced CL was performed using adult polymorphonuclear leukocytes to react with the opsonized Z. The cord sera was found to contain 30-70% of normal concentrations of C3, factor B, properdin, B1H, and C3bINA. Mean opsonization as measured by CI. was decreased for cord sera when compared to controls; however, some NB sera demonstrated normal ability to opsonize Z. Opsonic activity varied significantly only with the βlH concentration of the serum. β1H, along with C3bINA, is known to regulate the activity of C3 and factor B in the AP so that the ratio of C3+factor B/βlH+C3bINA in non-NB's is approximately 1.0. In the cord sera of 200 uninfected NB's, however, this ratio was 1.3 (p < 0.001) suggesting an altered regulatory mechanism for the normal NB. Eight of 9 NB's who experienced systemic infection in the first few days of life had a ratio of AP components equivalent to the non-NB's. These data demonstrate that failure to develop a typical neonatal regulatory pattern may play a role in defective opsonic activity and that CL may be used to study this activity in NB sera. The ability of NB sera to opsonize Z, however, does not predict susceptibility to infection.
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Mcmillan, J., Spitzer, R., Weiner, L. et al. 950 ALTERNATIVE PATHWAY (AP) OPSONIC ACTIVITY OF NEWBORN (NB) SERA AS MEASURED BY CHEMILUMINESCENCE (CL). Pediatr Res 15 (Suppl 4), 601 (1981). https://doi.org/10.1203/00006450-198104001-00975
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DOI: https://doi.org/10.1203/00006450-198104001-00975