Fig. 2.

Fc receptor CD16 was functional on GPA NK cells, which also recognized immobilized rituximab. PBMCs from 17 GPA patients were cultured overnight on uncoated plates (w/o or no ab) or on plates coated with rituximab (RTX), infliximab (INX), or anti-CD16 in the presence of a fluorochrome-labeled anti-CD107a antibody. Thereafter, PBMCs were stained with a viability dye and fluorochrome-labeled antibodies against CD3, CD19, CD56, CD16, and CD69 and analyzed by flow cytometry. The gating strategy is shown in Additional file 1. NK cells were defined as viable CD3-CD19-CD56+ lymphocytes. a Exemplary histograms show the cumulative surface expression of CD107a during the incubation period and the surface expression of CD69 and CD16 at the end of the incubation period on NK cells originating from the same patient. b Summarizing dot plots of all patients. Degranulation was defined as [(% of CD107a+ NK cells after culture with therapeutic antibody) − (% of CD107a+ NK cells after culture without antibody)]. Friedman test confirmed significance (p < 0.0001, p < 0.0001 and p = 0.0010, respectively). Significant Dunn’s post tests are indicated by stars