IFNG and systemic lupus erythematosus: Interestingly, in vitro ICOS co-stimulation of peripheral T cells from patients with active SLE resulted in greatly enhanced IFN-γ production relative to normal controls, and ICOS ligation preferentially induced production of isotype-switched α-double-stranded DNA (α-dsDNA) Abs during co-culture with autologous B cells (118).