ASSESSMENT OF HEMOGLOBIN-DEPENDENT NEUROTOXICITY - ALPHA-ALPHA CROSS-LINKED HEMOGLOBIN

Adult human hemoglobin A(0) (HbA(0)) has been shown to be neurotoxic, and we wish to report on similar studies conducted using a modified he moglobin, which has been crosslinked between the alpha subunits (alpha -alpha Hb). Cortical cell cultures were prepared from fetal Swiss-Webs ter mice at 15-16 days gestation. Mature cultures (days in vitro, 12-1 6) were exposed to alpha-alpha Hb in a defined medium for 24-48 hours at 37 degrees C. Low micromolar amounts of alpha-alpha Hb were neuroto xic in a concentration-dependent fashion. This toxicity was attenuated by the antioxidants Trolox and U-74500A and by the iron chelator defe roxamine. The hemoglobin-binding protein, haptoglobin, also completely blocked alpha-alpha Hb-dependent neurotoxicity. The latter result was unexpected because complex formation between alpha-alpha-Hb and hapto globin was not detected using assays of haptoglobin fluorescence and h emoglobin peroxidase activity.