Complement Levels in Brazilian Children During and After Meningococcal Meningitis

Abstract

ROXO Jr. P et al. Complement levels in Brazilian children during and after meningococcal meningitis. CLINICS 60(2):127-130, 2005. PURPOSE:To evaluate the functional activity of the classical and alternative pathways of the complement system and the levels of C3, C4, and factor B during the first episode of meningococcal infection and during the convalescence period.PATIENTS AND METHODS: Ten Brazilian children ranging in age from 8 months to 8 years, admitted from 1991 to 1993 with a clinical-laboratory diagnosis of meningococcal meningitis, were studied during acute infection (up to 7 days from diagnosis) and during the convalescence period (1 to 6 months after the acute episode). C3, C4, and Factor B were measured using nephelometry, and the lytic activity of classical and alternative pathways were evaluated by a kinetic method and expressed as the time needed to lyse 50% of an erythrocyte suspension (T1/2, expressed in seconds). Low T1/ 2 values for classical and alternative pathways correlate with high activities of the classical and alternative complement pathways, respectively.RESULTS: A significant difference was observed between the alternative pathway lytic activity during infection and the convalescence period (282 vs 238 seconds, respectively, P = .01). No differences were detected in the other complement parameters analyzed.CONCLUSIONS: In the presence of meningococcal meningitis, the alternative pathway is preferentially activated. This is probably due to the greater ability of the meningococcal endotoxin to activate this pathway in vivo.