BTLA and granulomatosis with polyangiitis: Next, the expression profiles of both inhibitory (FcγRIIB, CD22, BTLA, PD-1, FcRL5, and CD5) and stimulatory (CD40, ICOSL, BAFFR, TACI, CD21, and CD86) surface immune molecules were mapped across the B-cell populations in GPA patients and HCs.