Presentation: The B Lymphocyte Factor (BLyS) in Castleman’s Disease (2007)

151 The B Lymphocyte Factor (BLyS) in Castleman’s Disease

Background: Castleman’s disease (CD) is histologically associated with a plasma cell proliferation in the plasma cell and mixed forms. BLyS is known to favour the B cell and plasma cell proliferation.
Objective: To investigate the BLyS serum levels and its clinical, biological and histological correlations in patients with CD.
Patients and Methods: 26 patients with biopsy proven CD, 15 males, mean age 46±14.5 years, 7 patients with HIV infection, 9 with autoimmune disease and 3 with B cell non-Hodgkin lymphoma (B-NHL). Histological forms: 12 plasma cell (pcCD) forms, 11 mixed (mCD) forms and 3 hyaline-vascular (hvCD) forms. BLyS serum levels were measured by ELISA (Quantikine Human BAFF/BLyS Immunoassay R&D Systems) in sera of patients with CD compared to 22 healthy controls. IL6 (validated cut-off of positivity: 5 pg/mL) and VEGF (validated cut-off of positivity: 500 pg/mL) serum levels were measured by ELISA tests.
Results:
1°/ Mean BLyS serum levels were significantly higher in patients than in controls [2205±1497 vs 750±117 pg/mL, respectively; P<0.0001]. BLyS serum levels were higher in patients with associated autoimmune disease [2901±1522 vs 1836±1389; P=0.03], lymphoma at presentation [3641±1856 vs 2017±1384; P=0.04] and HIV infection [3188±1579 vs 1842±1330; P=0.04]. BLyS serum levels were 1386±182 for hvCD, 1888±1577 for pcCD to 2595±1538 pg/mL for mCD [P=0.1]. BLyS serum levels were correlated positively with CRP levels [r=0.49; P=0.01] and ferritin levels [r=0.44; P=0.07], and negatively with haemoglobin levels [r= -0.47; P=0.016]. There was no correlation with immunoglobins levels, VEGF or IL6 serum levels or haemolysis.
2°/ After analysis of BLyS serum levels distribution in patients with CD, 11 patients (7 mCD and 4 pcCD) had serum BLyS levels ≥2000 pg/mL [3756±925] and 15 patients <2000 [1067±336]. Patients with BLyS levels ≥2000 tended to be more often HIV+ [5/11=45.5% vs 2/15=13%; P=0.08], and to have an autoimmune disease [6/11=54.5 % vs 3/15=20%; P=0.1]. These patients had higher CRP levels [160.6±8 vs 56.8±50.5 mg/L; P=0.0006], ferritin levels [2924±3078 vs 1190±1732 µg/L; P=0.07] and lower haemoglobin levels [8.4±1.6 vs 10.9±2.7 g/dL; P=0.01]. After multivariate analysis, only CRP [P=0.01] and the presence of an autoimmune disease [OR=10.7; CI95%=1.1-107; P=0.04) remained significantly associated with serum BLyS levels ≥2000.
Conclusion: 1) BLyS serum levels are frequently elevated in patients with CD; 2) High BLyS serum levels in patients with CD are associated with the presence of an autoimmune disease and with markers of systemic inflammation. The role of BLyS in the plasma cell proliferation during CD is not excluded as the highest BLyS serum levels were detected in patients with pcCD and mCD and as plasma cells may express BLyS and it receptors.

 D. Sène, None; G. Carcelain, None; A. Delluc, None; M.C. Diemert, None; F. Charlotte, None; C. Deback, None; Z. Amoura, None; J.C. Piette, None; P. Cacoub, None.