[Development of the serum levels of complement during the first year of life]

Development of human C. system was studied by quantification of total serum hemolytical activity (CH50) and individual levels of C3, C4 and C5 in full term newborns. Comparison of results in newborn infants and their mothers sera is made. The ratios of neonatal-maternal sera concentrations were CH50, 0.29; C3, 0.61; C4, 0.51, and C5, 0.63. Serum concentrations of C3 and C4 reached maternal concentrations at twelve months of age. Serum concentrations of C4 and CH50 reached maternal levels at six months of age.