Susceptibility to lipid peroxidation and accumulation of fluorescent products with age is greater in T-cells than B-cells.
The age-related loss of immune function, which is primarily due to loss of T-lymphocyte function, is also associated with accumulation in spleen lymphocytes of autofluorescent products indicative of peroxidation damage. In this study, we examined T-cell membranes for age-related changes which could be related to lipid peroxidation. Using fluorescence spectroscopy of CHCl3:CH3OH membrane extracts, we observed that old T-cells have a 2-fold greater accumulation of fluorescent products than old B-cells and that young T-cells, when exposed to free radicals in an in vitro system, accumulate significantly more fluorescent products over time than young B-cells. We used fluorescence polarization to show that young T-cell membranes are more fluid than young B-cell membranes. However, T-cell membrane fluidity decreases with age, whereas B-cell membrane fluidity does not change; in old mice, T-cell membranes are significantly less fluid than old B-cell membranes. Using two-dimensional electrophoresis, we showed that membrane extracts of old T-cells contain many more proteins than extracts of young T-cells. Our results indicate that age-related changes occur in T-cell membranes which could be due to their increased susceptibility to lipid peroxidation and these changes may contribute to the age-related decline in immune function.
Hendricks
L C
LC
Department of Biochemistry, University of Nebraska College of Medicine, Omaha 68105.
Heidrick
M L
ML
D000375:Aging / Q000276:immunology*; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D005453:Fluorescence; D005609:Free Radicals; D015227:Lipid Peroxidation; D008297:Male; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*
D005609:Free Radicals; D008565:Membrane Proteins