CD46 and systemic lupus erythematosus: The idea that much more work is required to understand the complex in vivo role of autocrine complement in health and disease is underpinned by the finding that, unexpectedly, increased numbers of IL‐10‐producing (and not IFN‐γ producing) T cells after CD3+CD46 activation correlate with the highest SLEDAI score in SLE patients (Fig. 2B).