Inactive disease in lupus patients is linked to autoantibodies to type-I interferons that normalize blood IFNα and B cell subsets

Systemic Lupus Erythematosus (SLE) is characterized by a prominent increase in expression of type-I interferon (IFN)-regulated genes in 50-75% of patients. Here we investigate the presence of autoantibodies (auto-Abs) against type I IFN in SLE patients and their possible role in controlling disease severity. We report that out of 491 SLE patients, 66 had detectable anti-IFN-auto-Abs. The presence of neutralizing anti-IFN-auto-Abs correlates with lower levels of circulating IFN protein, inhibition of IFN down-stream signalling molecules and gene signatures and with an inactive global disease score. Previously reported B cell frequency abnormalities, found to be involved in SLE pathogenesis, including increased levels of immature, double negative and plasmablast B cell populations were partially normalized in patients with neutralising anti-IFN-auto-Abs compared to other patient groups. We also show that sera from SLE patients with neutralising anti-IFN-auto-Abs biases in vitro B cell differentiation towards classical memory phenotype, while sera from patients without anti-IFN-Abs drives plasmablasts differentiation. Our findings support a role for neutralising anti-IFN-auto-Abs in controlling SLE pathogenesis and highlight their potential efficacy as novel therapy.