Membrane protein organization of peripheral blood lymphocytes from healthy young and aged adults

Membrane-mediated events are important in the function of lymphocytes and age-dependent changes in the integrity of lymphocytic membranes could account, in part, for the loss of immune responsiveness observed in the aged. To test the hypothesis that membranes of lymphocytes undergo age-dependent change in their biophysical parameters, a method utilizing electron spin resonance spectroscopy was developed as a means to assess the dynamic character of lymphocytic membrane protein organization. This methodology allowed identification of weakly (W) and strongly (S) immobilized membrane proteins. By taking the ratio of these two protein classes (W/S ratio), lymphocytes from elderly were found to have a slightly increased W/S ratio when compared to young adults, but this difference was not statistically significant. This study contrasts with previous reports which indicated that the lipid microenvironment of lymphocytes undergoes age-dependent change. Thus, despite previously reported age-related changes in the biophysical parameters of lipids in resting lymphocytes, this alteration does not appear to affect the dynamic character of membrane-bound proteins.