Fluorescence studies of red blood cell membranes from individuals with Huntington's disease

Fluorescence spectroscopic methods were used to investigate and compare the properties of erythrocyte membranes from individuals with Huntington's Disease (HD) and from normal individuals. Erythrocyte ghosts were labeled with four different fluorescent probes: 1,6-diphenylhexatriene (DPH); 6-lauroyl-2-(dimethylamino)-naphthalene (Laurdan); 2-(4-maleimide anilino)-naphthalene-6-sulfonic acid (MIANS) and 5-(iodoacetamidoethyl)aminoaphthalene-1-sulfonic acid (IAEDANS). DPH is sensitive to the microviscosity of the membranes. Laurdan is highly sensitive to the polarity and relaxation time of its environment. MIANS and IAEDANS both react covalently with sulfhydryl groups in membrane proteins. Erythrocyte membranes were labeled separately with each of these four probes, and we measured the centers of gravity of the fluorescence emission, the fluorescence anisotropies, and the fluorescence lifetimes. In 10 separate experiments, including a total of 24 patients and 14 control individuals, we found no significant differences between the two groups for any of the probes or spectral parameters. These results do not support the existence of a "generalized membrane defect" in individuals with HD.