Complement profile in neonates of different gestational ages.
Blood levels of regulators of the complement system in preterm babies were reported in few studies only. The aim of this study was to set up a complement profile in premature and term babies focusing on the development of blood levels of MBL, key regulatory proteins and on classical pathway activity, which may allow an estimation of potential susceptibility to infection. Complement activity (CH50), levels of mannan-binding lectin (MBL), complement regulators (factors H and I, C1 inhibitor, properdin) and C3a as marker of complement activation were assessed in three groups of healthy newborns: (1) prematures (≤34 weeks); (2) late prematures (>34-<37 weeks) and (3) term neonates (≥37 weeks). CH50 increased with gestational age with lower titres in cord blood than in day 5 post-delivery venous blood. MBL concentrations were not significantly different among groups. Quantitative and functional C1 inhibitor were below adult normal range in prematures <34 weeks and lower in cord blood as compared to day 5. Factor I, factor H and properdin remained below adult values in all groups. Low C3a levels excluded that low complement titres were due to activation-induced consumption. These results demonstrate the relative immaturity of the complement system and its regulation, especially in premature infants.
Department of Dermatology, Faculty of Medicine, University of São Paulo, São Paulo, Brazil; Faculty of Medicine ABC, Outpatient Clinic of Recurrent Infections, São Paulo, Brazil.
A S
AS
Grumach
M E
ME
Ceccon
R
R
Rutz
A
A
Fertig
M
M
Kirschfink
D000328:Adult; D003167:Complement Activation; D050718:Complement C1 Inhibitor Protein / Q000235:genetics / Q000378:metabolism*; D015926:Complement C3a / Q000235:genetics / Q000378:metabolism*; D017242:Complement Factor H / Q000235:genetics / Q000378:metabolism; D015941:Complement Hemolytic Activity Assay; D005260:Female; D005340:Fibrinogen / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D037601:Mannose-Binding Lectin / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D047928:Premature Birth / Q000276:immunology*; D011414:Properdin / Q000235:genetics / Q000378:metabolism
D050718:Complement C1 Inhibitor Protein; D037601:Mannose-Binding Lectin; D011414:Properdin; D015926:Complement C3a; D017242:Complement Factor H; D005340:Fibrinogen