C3 and C4 complement system components as biomarkers in the intermittent atopic asthma diagnosis.

OBJECTIVE To analyze serum C3 and C4 complement system components with a view to their possible utility as biomarkers of intermittent atopic asthma. METHODS Serum levels of the C3 and C4 complement components were assayed in 70 children aged from 3 to 14 years and with a history of "wheezy chest." After 2 years' outpatients follow-up and after application of inclusion and exclusion criteria, the children were divided into two groups: 40 children with intermittent atopic asthma and 30 children without asthma. None of the children in either group were treated with inhaled or systemic corticosteroids or long-acting bronchodilators. The two groups had similar ages according to Student's t test. The C3 and C4 component test results followed a normal distribution and were therefore compared using Student's t test with significance set at p < 0.05. RESULTS The results for the group with intermittent atopic asthma were significantly elevated for C3 in 85.0% of the children, for C4 in 87.5% of the children, for both C3 and C4 in 72.5% of the children, and for either C3 or C4 in 97.5% of the children, when compared with the results for the children without asthma from the same age group. CONCLUSIONS We observed an increase in the serum levels of the C3 and/or C4 components of the complement system in the majority of the patients with intermittent atopic asthma studied here, when compared with the results for children in the same age group without asthma. We conclude that the presence of elevated C3 and/or C4 complement components could represent a biomarker for diagnosis of intermittent atopic asthma.