CD8A and systemic lupus erythematosus: Although KYN accumulation in CD8+ T cells and sera of B6.TC/Rab4AQ72L mice occur with increased demand for pyridine nucleotides during lupus pathogenesis, all of which are mTOR-dependent, further mechanistic studies that connect KYN metabolism with mitochondrial dysfunction and metabolic flux through the TCA cycle seem warranted.