IL6 and thymoma: Pre‐incubating positive APECED or thymoma patients’ sera with recombinant human (rh) IL‐6 completely blocked subsequent binding to IL‐6 in LIPS assays (p < 0.01), whereas a control cytokine, rhIL‐IFN‐γ, had no such effect (p > 0.05; Fig. 2A).