Activation of blood coagulation in plasma from chronic urticaria patients with negative autologous plasma skin test

Abstract

Background Skin reactivity to the intradermal injection of autologous serum (autologous serum skin test – ASST) and/or plasma (autologous plasma skin test – APST) is thought to identify chronic urticaria (CU) patients with an autoimmune/autoreactive disease. Immune‐mediated inflammation and coagulation are strictly linked, and coagulation activation has been described in CU patients as shown by the elevation of plasma prothrombin fragment F1 + 2 and, in severe cases, of d‐dimer as well. Objective The aim of this study was to evaluate whether the coagulation cascade is activated in APST‐negative CU patients as it has been described in CU patients with an autoreactive disease. Methods A total of 43 adults with CU (M/F 15/28; mean age 43.5 years; 16 APST‐negative patients and 27 APST‐positive) and 30 healthy subjects were studied. Prothrombin fragment F1 + 2, d‐dimer and C‐reactive protein (CRP) plasma levels were measured by ELISA. Results Prothrombin fragment F1 + 2 and d‐dimer were elevated in seven of 16 APST‐negative CU patients. The activation of the coagulation cascade was associated with disease severity. Men were more prevalent in idiopathic than in autoreactive CU patients (M/F: 10/6 vs. 5/22; P < 0.001). In patients with APST‐negative CU, mean F1 + 2 level [242.8 ± 33.7 pmol/L (ESM)] was higher than in normal controls (151.8 ± 9.09 pmol/L; P = 0.002) but lower than in autoreactive patients (526.2 ± 97.8 pmol/L; P = 0.05). Similarly, mean d‐dimer level was higher than in normal controls (484.2 ± 148.3 ng/mL vs. 229.5 ± 16.7 ng/mL; P = 0.03) but lower than in autoreactive patients (1142.2 ± 317.4 ng/mL; P = 0.05). In contrast, mean CRP was lower than in autoreactive patients (1.06 ± 0.32 μg/mL vs. 3.09 ± 0.74 μg/mL; P = 0.02) but not different from normal subjects (0.78 ± 0.09 μg/mL; NS). Conclusion Autologous plasma skin test‐negative CU prevails in men; in these patients the coagulation cascade is activated although with a lower intensity than in patients with autoreactive disease.