Erythropoietic inhibitors in uremic serum.

The anemia of chronic renal failure was studied by assessing the inhibitory effect of uremic serum on the proliferation of normal human marrow erythroid progenitor cells (CFU-E and BFU-E) using an in vitro colony assay. Of 10 uremic patients studied, sera from 9 inhibited CFU-E colony growth by 29-100%, sera from 8 inhibited BFU-E colony growth by 23-94%, and sera from all inhibited either CFU-E or BFU-E. The sera were fractionated by Sephacryl gel filtration and the fractions were added to the marrow cultures. Almost all the suppressive activity against erythroid colony growth was detected in fractions with mol. wts of from 47,000 to greater than 150,000 daltons and this indicates the presence of several high mol. wt inhibitors. Serum fractionation by Sephacryl gel was useful in confirming the presence of uremic inhibitors of erythropoiesis, and in concentrating them to a degree that will allow detailed characterisation studies.