No abstract

An ability to maintain high levels of fetal hemoglobin (Hb F) has been associated with the amelioration of the clinical severity of the sickle cell disease (SS). Clinical efforts to increase the Hb F level of the patients have, however, yielded variable therapeutic response. In an attempt to further elucidate the underlying molecular basis, in vitro Hb F synthesis was studied in erythroid progenitor (BFU-E) cells obtained from SS patients and their heterozygous (AS) relatives with varying genetic backgrounds. This allows us to study the Hb F biosynthesis pattern uncomplicated by the influence of the preferential survival of "F cells" in vivo. The Hb F levels and the relative concentrations of its constituent gamma globin chains, G gamma and A gamma, were assayed using the reversed phase HPLC method. A percentage increase in the fetal hemoglobin content was observed in the lysates of the erythroid progenitor cells relative to the circulating peripheral blood erythrocyte values in SS patients and their AS relatives with different beta S haplotypes reflecting the intrinsic capacity of fetal hemoglobin synthesis in these subjects. No such increase was observed in the patient with the Mor haplotype. Furthermore, the Hb F synthesized in the BFU-E colonies was more of the adult type, as evidenced by the decrease in the percent G gamma level relative to the corresponding peripheral blood values of the subjects in all the haplotype groups studied. The Mor haplotype was again an exception, synthesizing fetal hemoglobin more of the fetal type.

No abstract

No abstract

Embryonic globin chains were found to be synthesized in vitro by the BFU-E colonies derived from adult sickle cell anemia (SS) patients, their heterozygous relatives as well as a few normal controls. In the absence of sufficient material for conducting direct structural analyses of these peptides, they were confirmed by evaluating the co-migration of the epsilon and zeta-chains with the corresponding structurally characterized globin chains obtained from K562 cell lysates on a reversed phase high performance liquid chromatogram. The presence of zeta-chain was also confirmed using an immunologic procedure. Furthermore, significant 35S-methionine incorporation peak was observed corresponding to the zeta-chain synthesized by the BFU-E-derived colonies implying an active synthesis of this embryonic globin chain in BFU-E cells obtained from hemopoietically adult persons.