Despite many studies focused on involvement of T cell in pathogenesis of Takayasu arteritis (TaK), very few have explored the role of B cells. Hence, we sought evidence of B cell involvement in a large cohort of TaK by measuring serum levels of B cell survival factors activation factor (BAFF) and A proliferation inducing ligand (APRIL). Serum BAFF and APRIL levels were measured by ELISA in 50 patients and 48 healthy individuals, and further assessed for correlation with outcome measures, such as Indian Takayasu Clinical Activity Score-ESR (ITAS-ESR) and Takayasu arteritis Damage score (TADS). Forty women and ten men of median age 26 (11-52) and disease duration of 3 years (0.1-22) were studied. Type V disease was the most common subset (n = 31), while type I, II, III, and IV was seen in ten, four, three, and two patients respectively. Serum APRIL levels were raised in patients as compared to healthy controls [2087.5 pg/ml (1480.0-2279.0) vs. 1288.64 pg/ml, (844.2-1632.9) p = 0.01]. Median serum APRIL level was also raised in patients with active disease (n = 24) as compared to inactive disease (n = 26) 2098.79 pg/ml, (1930.75-2768.75) vs. 1802.5 pg/ml, (1066.75-2098); p = 0.03). Serum BAFF levels were not raised in patients with TaK when compared to healthy Individuals. Neither BAFF, nor APRIL levels correlated with disease activity (ITAS-ESR) or TADS. Elevated APRIL levels in active TaK suggest probable role of B cells in pathogenesis.
Keywords: B cell; Indian Takayasu Clinical Activity Score; Large vessel vasculitis; Pathogenesis of Takayasu arteritis.