RED-BLOOD-CELL MEMBRANE AND DENSITY CHANGES UNDER AMBIENT AND HYPOXICCONDITIONS IN TRANSGENIC MICE PRODUCING HUMAN SICKLE HEMOGLOBIN

Red blood cells (RBC) from patients with sickle cell disease (SCD) are characterized by membrane lesions caused by cell sickling and oxidati ve damage due to denatured hemichromes. We have developed three lines of transgenic human sickle hemoglobin (Hb S) mice, which produce 30, 5 0, and 80% human beta(sickel) globin (h beta(s)), by crossing transgen ic progeny with nonthalassemic, heterozygous, or homozygous beta-thala ssemic mice, respectively. Transgenic mice that produce Hb A, develope d in a similar fashion, were used as controls. RBC from each transgeni c line were examined for pathologic changes. RBC from 50 and 80% h bet a(s) mice sickle upon deoxygenation in vitro while RBC from 30% h beta (5) mice and all Hb A mice do not. Density gradients of RBC from each Hb S line, including those from 30% h beta(s) that do not sickle, show broad distributions with increased dense fractions, similar to those of patients with SCD. RBC from Hb S lines exhibit elevated membrane-as sociated denatured hemoglobin (MADH) levels (0.250 +/- 0.080%) when co mpared to RBC from nontransgenic (0.073 +/- 0.021%) and transgenic Hb, A (0.062 +/- 0.033%) mice. Elevated MADH levels in RBC from the 30% h beta(s) line suggest that membrane changes occur even though these ce lls do not sickle. These Hb S-dependent pathologic changes suggest tha t transgenic Hb S lines may be useful for the study of not only RBC si ckling in vivo but also membrane oxidative damage and other chronic ch anges attributed to abnormal properties of both oxygenated and deoxyge nated Hb S.