Consistent with this possibility, IL‐6 classic signalling was shown to be obligate and sufficient for the induction of systemic disease in a murine model of human arthritis.77 In contrast, for asthma and other allergic diseases, the disease‐protective allele is rs2228145:A, which inhibits IL‐6 trans‐signalling but promotes classic signalling. Here, IL6 is linked to arthritic joint disease.