CR2 and leprosy: To evaluate whether this decrease in CD21+ B cells in the blood of ENL+ could be related to an increase in these cells in the skin lesion tissue, we measured the expression of CD21 in skin lesions of a set of leprosy patients with active RR (n = 3), active ENL (n = 3), and no reaction (BT, n = 7; BL/LL, n = 3).