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The presence of minute amounts of embryonic zeta-globin chains in adult hemolysates is a marker for carriers of alpha-thalassemia-1 resulting from (--SEA/) deletion. Recently, we developed a murine monoclonal antihuman embryonic zeta-globin chain antibody, 8E8. By using this antibody, we have now established a slot-blot immunobinding assay for the rapid detection of zeta-globin chains in adult hemolysates. zeta- globin chains were found to be present in 30 blood samples obtained from individuals who were carriers of alpha-thalassemia-1. In another 30 blood samples from individuals who were not carriers of the (--SEA/) deletion, zeta-globin chains were not detected. This simple diagnostic test can be used in appropriate populations to identify those couples at risk of conceiving fetuses afflicted with the Hb Bart's hydrops fetalis syndrome due to homozygous alpha-thalassemia.

A rapid spectrophotometric assay capable of detecting the hemoglobin content of 1000 mature erythrocytes has been utilized to quantitate the total hemoglobin synthesized by the progeny of circulating human erythroid progenitors in both the plasma clot and methylcellulose culture systems. The pronounced variation in the effect of different erythropoietin preparations on the hemoglobin content of cultured human peripheral blood bursts, previously described in a subjective manner, has been objectively quantitated. Further experiments demonstrated that both lymphocyte conditioned media and dexamethasone substantially increased the total hemoglobin synthesized by the progeny of cultured erythroid progenitors. The elevated amount of hemoglobin present in erythroid cultures containing either lymphocyte conditioned media and/or dexamethasone was due to both increased colony numbers and colony size. Assay of the total hemoglobin content per erythroid culture is an accurate, sensitive, measure of erythropoiesis in vitro and should be a valuable adjunct to the enumeration of BFU-E-derived erythroid colonies.

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Ten patients with preleukemia were studied by the erythroid cell clonal culture technique. In nine of these patients, erythroid colonies derived from peripheral blood BFU-E were not observed, while the other patient had markedly decreased peripheral blood BFU-E-derived erythroid colonies in vitro. In three patients, marrow cells were also cultured and no BFU-E-derived erythroid colonies were detected. These studies indicate that immature erythroid progenitor cells, BFU-E, in patients with preleukemia are either markedly decreased in number or grossly defective in their proliferative or differentiative capacities.