Increased serum complement C3 and C4 concentrations and their relation to severity of chronic spontaneous urticaria and CRP concentration

Chronic spontaneous urticaria (CU) is associated with activation of the acute phase response (APR). Nevertheless, APR-associated proteins have not been well characterized as potential biomarkers of the disease severity. To assess the pattern of complement proteins C3 and C4 - the acute phase reactants in patients with CU. C3, C4 and CRP concentrations were measured in serum of 70 patients showing different degrees of urticarial severity as well as in 33 healthy subjects. Serum C3 and C4 concentrations were significantly increased in CU patients as compared with the healthy subjects and exceed the normal lab range by about 5% and 10%, respectively. Significant differences were found between patients with mild and increased CU severity. In addition, significant correlations were observed between C3, C4 and CRP concentrations. More severe CU is characterized by higher production of C3 and C4 complements accompanied by parallel changes in CRP concentration.