Membrane Studies in Huntington's Disease: Steady State and Time-Dependent Fluorescence Spectroscopy of Intact Lymphocytes

Abstract

Abstract: Recent evidence suggests that a membrane abnormality, expressed in peripheral tissues such as the lymphocyte, may be present in Huntington's disease (HD). Both steady state and time-dependent fluorescence spectroscopic methods were performed on lymphocytes from patients with HD and from age- and sex-matched controls. Lymphocyte membrane dynamics were studied, using fluorescence probes with known specificity for certain membrane areas. These probes included 4-phenylspiro(furan-2(3H)-1′-phthalan)-3,3′-dione (fluorescamine), which binds to surface membrane primary amines, 1–8-anilinonaphthalene sulfonate (1,8-ANS), which inserts at the aqueous-hydrocarbon interface, and 12(9) anthroyl stearate (12(9)AS), which inserts deep in the hydrocarbon core. Steady state fluorescence studies, using fluorescamine, 1–8 ANS, or 12(9)AS, revealed no significant difference between intact HD and control lymphocytes. Time-dependent energy-transfer polarization studies for fluorescamine (tryptophan → fluorescamine) did, however, reveal a slower time decay of I₁/I for intact HD lymphocytes as compared with controls. This time-dependent difference may relate to alterations in translational (lateral) and angular mobilities of membrane donors (tryptophan) relative to acceptors (fluorescamine) in intact HD lymphocytes. Such observations support the concept of a membrane abnormality in HD.