A chromatofocusing column was used to separate burst-promoting activity (BPA) and erythropoietin (Ep) activity in sera from patients with aplastic anemia and, interestingly a fraction containing a considerable level of BPA without Ep activity was found at around pH 5.0. Another fraction at lower pH contained both activities. This is the first report of the existence of a fraction with BPA but without Ep activity in sera from aplasia patients. In trying to measure BPA in sera and urine, a new assay procedure was used involving counting the number of erythroid bursts in normal human marrow cell cultures initiated with test samples to which 1-2 units of standard Ep were added 5-6 days later. Separation of BPA from Ep activity in patients sera was also attempted by Sephadex G-100 but this was unsuccessful due to the presence of inhibitors to burst formation. Also, in a urine separation, BPA and Ep activities were eluted in the same fraction. Sephadex G-100 chromatography gave results which seemed to indicate separation of BPA from Ep activity, however, this may have been due to the presence of inhibitor(s). This idea was supported by the fact that the peaks of both activities coincided when a urine preparation containing no inhibitors was tested.
Anemia, Aplastic Animals