Effects of TNF-α on human and murine primary erythroid cells.

(A) Human CD34⁺ cells were cultured in EPO or in EPO with 0.2, 2.0, or 20.0 μg/mL neutralizing TNF-α antibody for 7 days and assessed for glycophorin A expression by flow cytometry. Increasing amounts of antibody resulted in an increase in the number of glycophorin A–positive cells (lanes 2-4), whereas the addition of control IgG had no effect (lane 5). (B) Total bone marrow isolated from TNF-α wild-type (WT) (lanes 1-3) and TNF-α^−/− (lanes 4-6) mice was incubated in EPO alone (lanes 1, 4) or EPO with 1 or 10 ng/mL TNF-α (lanes 2, 3, 5, 6) in semisolid media. The number of BFU-Es was counted 8 days after the start of the experiment and is expressed as number of BFU-Es detected per 30-mM plate.