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

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 mu g/mL vs. 3.09 +/- 0.74 mu g/mL; P = 0.02) but not different from normal subjects (0.78 +/- 0.09 mu g/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.