TNF and systemic lupus erythematosus: Serum and urine ferritin levels of healthy (N = 3), SLE (N = 5), and LN patients (N = 5), as measured by the protein arrays, were analyzed for possible correlation with serum levels of interleukin (IL)-1α, IL-6, and tumor necrosis factor (TNF)α, also interrogated on the same arrays.