Controlled secretion of dimeric erythropoietin does not induce antibodies.

Four β-thalassemic mice were injected with a mix of 2 μg ptet-Off and 20 μg ptet-mEpoD. Hematocrit (A) and erythropoietin levels (B) were determined 38 and 26 weeks, respectively. Mice were given tetracycline (horizontal black rectangles) from weeks 4 to 8, 16 to 20, and 26 to 29.5.