Age-associated B cells (ABCs), which are known to be associated with autoimmunity, expand gradually with age in healthy individuals but proliferate robustly in response to TLR7 or TLR9 stimulation, and may thus result in the production of autoreactive immunoglobulins, leading to autoimmune disease flare or new onset disease (39, 40). This evidence concerns the gene TLR9 and autoimmune disease.