Abstract
Extract: C3PA (factor B) concentrations taken as an indication of alternate pathway development for neonates and adults were compared. The mean level for umbilical cord sera was 39 ± 2%, with a range of 19.5–77.5%. The normal adult mean level was 74 ± 4%, with a range of 43–108%. The difference between the two is highly significant (P < 0.001). The ratio of neonatal C3PA to adult C3PA is 0.52 ± 0.10. In only one case was the newborn level greater than the mean adult value. There is positive correlation, r = 0.18, with gestational age, although it falls short of statistical significance (P > 0.1). There were no differences between the male and female neonates. C3PA liters were compared with C3 concentrations and so plotted. Although there was a positive correlation, r = 0.22, it was not statistically significant (P = 0.1).
In an infant with gram-negative septicemia, the C3PA concentrations were much greater than the mean value found in normal cord sera. They were also greater than the mean value for normal adult C3PA tilers, the multiple being 1.8–2.5. On first determination, after 2 days of normal to slightly elevated temperatures, a value of 132 ± 6% was found. The second determination with a spike to 101.5° F, and gave the highest of the three liters, 185 ± 4%. At the same time that the C3PA levels reached this peak, Ihe fever dropped lo normal. At the time of the last delermination, the C3PA levels had returned to that of the original sample, 125 ± 4%.
This sludy demonstrates lhal Ihe cord sera of Ihe normal term neonate is deficient in C3 and C3PA when compared with adult controls. Neither C3 nor C3PA correlated with gestational age. C3PA levels increase steadily as C3 titers increase and comparable ratios to adult values indicate that the alternate pathway is probably maturing at the same rate as the classic pathway. The results in the septic infant may represent a response to an inflammatory condition (acute phase phenomena), a block in alternate pathway expression, or synthesis beyond increased C3PA catabolism.
Speculation: The development of the alternate pathway probably parallels the maturation of the organ systems responsible for its synthesis, although placental mechanisms (equilibration or production of an inhibitor substance) have not been excluded as a factor in Ihe status of this system in the neonate. Investigation of Ihe abnormal findings in an adequate sample of neonates wilh gram-negalive is indicated to assess Ihe role of the alternate pathway of complement activation in the pathogenesis and prognosis of this condition in the neonate.
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Feinstein, P., Kaplan, S. The Alternative Pathway of Complement Activation in the Neonate. Pediatr Res 9, 803–806 (1975). https://doi.org/10.1203/00006450-197510000-00012
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DOI: https://doi.org/10.1203/00006450-197510000-00012
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