TLR9 and systemic lupus erythematosus: Recently reported B cell populations called double negative 2 (DN2) cells (IgD-, CD27-, CD11c +  + , and CXCR5lo) or CD11c +  + T-bet + B cells, which are expanded in patients with SLE [10, 11] have been proven to encompass autoreactive ones and believed to be generated through TLR7 or TLR9 stimulations with the help of some cytokines [12, 13].