COMPLEMENT-SYSTEM IN HEALTHY TERM NEWBORNS - REFERENCE VALUES IN UMBILICAL-CORD BLOOD

Activation of the complement system occurs in several diseases;For rel iable identification of complement activation in neonates, we establis h reference ranges of several components in cord blood of healthy term newborns. For this study, cord blood samples were taken from 125 heal thy term newborns. Concentrations of C1r, C2, C5, C7, Properdin, and f actors D, H, and I were determined by single radial immunodiffusion. C 3a and C5a were measured by specific EIA and complement function was m easured by hemolytic assays. The results were expressed as 5th percent ile, median, and 95th percentile. The following respective concentrati ons were found: Clr: 27, 47, 65 mg/l; C2: 12.0, 18.0, 24.0 mg/l; C5: 6 4, 92, 127 mg/l; C7: 32, 60, 89 mg/l; Properdin: 5.6, 9.7, 14.2 mg/l; factor D: 3.6, 5.2, 7.3 mg/l; factor H: 178, 234, 296 mg/l; and factor I: 15, 24, 32 mg/l. The functional activity of the whole complement s ystem was 24%, 43%, 97% and for the alternative pathway 39%, 58%, 76%. The concentration of the activated split products C3a was 4, 65, 255 mu g/l and of C5a, 0.11, 0.26, 1.19 mu g/l. These reference values may be important for the detection of deficiencies of native complement p roteins or perinatal processes leading to an activation of the complem ent system.