Activity of Classical and Alternative Pathways of Complement in Preterm and Small for Gestational Age Infants

Abstract

SummaryComplement activity was compared in 50 low birth weight infants divided into appropriate and small for gestational age groups; the influence of birth weight and gestational age on complement development was also investigated. CHW and kinetics (tHso) of both classical and alternative pathway activity of complement, C3, and Factor B levels were significantly higher in small for gestational age infants (classical pathway CHs, 630 HU/ml f 184 SD, C P tHs, 77 min + 47; aternative pathway CHS0, 44.8 HU/ml & 11.3; AP tHso, 56 min f 43; C3, 73.98 mg/dl f 12.68; and Factor B, 13.17 mg/dl 2 3.67) than in weight-matched appropriate for gestational age infants (CP CHW, 523 HU/ml 2 152; C P tH9, 105 min + 49; AP CHW, 38.8 HU/ml f 13; AP tHW, 90 min 2 53; C3, 58.14 mg/dl f 9.43; and Factor B, 9.32 mg/dl+ 1.73). Complement values were lower in low birth weight infants than in adult controls ( P < 0.001 in all cases). All complement parameters were mainly correlated with gestational age; CHso values of the classical and alternative pathways were also highly correlated with each other

Neutrophil Production and Function in Newborn Infants

“…The importance of the CR3/Mac-1 receptor for neutrophil bactericidal function is again demonstrated by its absence in patients with leucocyte adhesion deficiency, in whom cells not only have chemotactic defects but also show defective cytocidal activity in vitro (Todd & Freyer, 1988). CR3 may have particular importance for neonatal neutrophil phagocytosis in the setting of low type-specific antibody and opsonin deficiencies in term neonates (Geelen et al, 1990;Droussou et al, 1995) and severe hypogammaglobulinaemia (Ballow et al, 1986) and deficient complement activity (Kovar et al, 1983;Notarangelo et al, 1984) in preterm infants. Its ability to bind to bacteria through lectins on their surface may compensate for lack of opsonization.…”

Phagocytosis of neonatal pathogens by peripheral blood neutrophils and monocytes from newborn preterm and term infants

“…Hypocomplementemia is suggested to be critical in preterm infant phagocytic function (20). We therefore investigated the role of complement by adding whole blood to pHrodo-labeled bacteria with or without rabbit complement (RbC) and comparing the nonopsonic phagocytic capability of each sample and the potentially additive effect of exogenous complement.…”

Opsonic Activity of Cord Blood Sera against Various Species of Microorganism

“…The main reason for these discrepancies lies in the use of different assays, different types of particles, particle size, and different serum concentrations. Concentrations of complement components important for the opsonization of various microorganisms in newborns were found to be relatively low compared with the levels in adults; however, normal and even elevated levels of complement proteins have also been reported (18)(19)(20)(21)(22)(23)(24)(25)(26)(27).…”