To date, at least five antagonistic anti-CD40 mAbs have entered clinical trials for various autoimmune diseases, including Graves' hyperthyroidism (Kahaly et al., 2019), primary Sjogren's syndrome (Fisher et al., 2017), rheumatoid arthritis (Visvanathan et al., 2016), plaque psoriasis (Anil Kumar et al., 2018), Crohn disease (Kasran et al., 2005), and ulcerative colitis (NCT03695185), as well as for transplant rejection (Farkash et al., 2019). Here, CD40 is linked to autoimmune disease.