ANALYSIS OF PERIPHERAL-BLOOD LYMPHOCYTE CELL-SURFACE DENSITY OF FUNCTIONAL AND ACTIVATION-ASSOCIATED MARKERS IN YOUNG AND OLD HEMODIALYSIS-PATIENTS

Aging has been associated with specific shifts in various peripheral b lood immume competent cell subsets. As part of pre-transplant immune p rofile evaluation possible parallel age-related changes in mean T-cell surface density of several cluster differentiation and activation lin ked antigens were analyzed in 150 patients with end stage renal diseas e on chronic hemodialysis. Patients were divided into 2 groups: group 1-114 patients 40 years old or younger and group 2-36 patients 55 year s old or older. Peripheral blood CD3+, DR+, CD3+DR+, CD4+, CD4+DR+, CD 8+, CD8+DR+, CD56+, CD8+CD56+, CD3+IL-2-R+ and CD3+TR+ (interleukin-2 and transferrin receptors bearing CD3+ cells respectively), all mononu clear cells expressing IL-2-R and TR, and CD4+CD45+ cell subsets were analyzed and enumerated by 2-color flow cytometry. Subset relative lev els as well as absolute counts were recorded. Cell surface density com putation was performed using a computerized mathematical model based o n fluorescence intensity vector analysis and cell size score determina tion based on light scatter pattern from raw data obtained by flow cyt ometry studies. Younger age was significantly associated with higher a bsolute cell count of CD3+ (p <0.001), DR+ (p <0.05), CD4+ (p <0.01), CD8+ (p <0.005), CD3+IL-2-R+ (p <0.05), CD3+TR+ (p <0.03) and IL-2-R(p <0.05). Older patients had a slightly higher mean absolute count of CD4+CD45+ subset (p not significant) and significantly higher mean co unt for CD8+CD56+ cell subset (p <0.001). When cell subset levels were compared between the 2 groups as the relative fraction of cells expre ssing a given marker out of all mononuclear cells gated out by flow cy tometry, younger age was significantly associated with higher levels o f CD3+ (p <0.005), CD8+ (p <0.001), CD4+DR+ (p <0.004), CD3-TR+ (p <0. 05) and CD8+IL-2-R+ (p <0.05). In contrast, slightly higher subset lev els of CD56+ (p not significant), and significantly elevated levels of CD8+CD56+ (p <0.0019) and CD4+CD45+ (p <0.004) were observed in the o lder patients. Cell surface density analysis showed that younger patie nts had higher mean density per cell of CD3 (p <0.05), CD8 (p <0.001), IL-2-R on CD3+ cells (p <0.05) and TR on CD3+ cells (p <0.05). Mean c ell surface density of CD56 on all CD56+ cells as well as on CD8+ cell s was higher in older individuals (p <0.001 and p <0.003, respectively ). Similarly, the CD45 antigen expression on CD4+ cells was significan tly increased in older patients (p <0.002). These data suggest that in parallel to specific shifts in certain cell subsets seen in elderly i ndividuals on chronic hemodialysis, age-related changes in cell surfac e densities of functional cluster differentiation and activation assoc iated markers can be detected. Such changes may reflect the decline in cell-mediated immunity in older patients on chronic hemodialysis.