Noninducible basal Gc-MAF generation from plasma Gc-globulin by lymphocytes in male control subjects, osteopetrotic patient, and her parents. The patient showed complete lack of generation of Gc-MAF before transplantation, but after transplantation Gc-MAF generation was evident. (•), Controls; (⧫), father; (▴), mother; (○), op/op; (◊), op/op (RX).