CD80 and lupus nephritis: Although kidney biopsies from patients with lupus nephritis showed strong B7-1 staining [9, 25], a recent trial comparing abatacept as add-on therapy to cyclophosphamide to a standard-of-care treated control group showed no improvement with the addition of abatacept, again disproving a role of B7-1 blockade in proteinuric kidney diseases [26].