CD27 and systemic lupus erythematosus: The expression of IFNλR on CD27+ memory B cells and the synergistic effects of IFNλ and TLR stimulation on B cell activation suggest that T3IFN signaling could play a crucial role in regulating ABC or DN2 cell activity in SLE, although a link between IFNλ signaling and ABCs or DN2s has not been established.