To determine the plasma levels of soluble CD30 (sCD30) in Wegener's granulomatosis (WG) patients, and to investigate the possible correlation of sCD30 with disease extent and activity.
sCD30 was determined by radioimmunoassay in 57 WG patients, 25 patients with rheumatoid arthritis (RA), 23 patients with bacterial infections and 21 healthy controls (HC). The extent and activity of WG disease were assayed according to disease extent index (DEI) and standard laboratory parameters.
Plasma sCD30 levels in generalized WG (22.5 +/- 1.5 U/mL), but not in initial phase WG (12.1 +/- 4.0 U/mL), were significantly increased compared with HC (8.8 +/- 0.9 U/mL, P < 0.0001). Furthermore, of 11 generalized WG patients who received long-term follow-up, sCD30 levels declined when the disease activity changed from active disease to remission (29.1 +/- 1.9 U/mL to 15.9 +/- 1.8 U/mL, P = 0.0001). Similar results were observed in the whole group of generalized WG, eg, sCD30 levels in active disease (29.4 +/- 1.4 U/mL) were significantly higher than in partial remission (17.9 +/- 1.9 U/mL, P < 0.001) and in complete remission (13.7 +/- 3.3 U/mL, P < 0.001). No significant difference was noted between complete remission and HC. In addition, sCD30 levels were correlated with other parameters of disease extent and activity such as DEI, plasma levels of sIL-2R, PR3-ANCA, ESR and CRP. The sCD30 levels were increased in RA patients compared with HC (15.2 +/- 2.1 U/mL, P < 0.05), but no correlation was found between disease activity parameters and sCD30 levels. In contrast, in patients with bacterial infections sCD30 levels (6.9 +/- 0.9 U/mL) were not significantly different compared with HC.
Plasma levels of sCD30 are not only significantly increased but also correlate with disease extent and activity in generalized WG. These findings suggest that sCD30 can act as a useful marker for evaluation of disease extent and activity, and that generalized WG may be associated with Th2-type immune response.