Age-related change in peripheral blood T-lymphocyte subpopulations and cytomegalovirus infection in the very old: the Swedish longitudinal OCTO immune study

Results from the previous times (Times 1-3) of the Swedish longitudinal OCT O immune study indicated that a combination of high CD8 and low CD4 percent ages and poor T-cell proliferation in PBL was associated with a higher 2-ye ar mortality in a sample of very old Swedish individuals. The combination o f immune parameters was closely related to an inverted CD4/CD8 ratio. In th e present study at Time 4 (T4) results are reported from the final follow-u p of this longitudinal study, 8 years after it was initiated in 1989. An ad ditional goal at this time point was to examine the immune system alteratio ns in the very old in relation to evidence of lymphocyte activation and cyt omegalovirus antibody status. In the present study immune system changes we re identified that suggest a loss of T-cell homeostasis, as reflected by a decrease in the number of CD4 cells and a very significant increase in the number of CD8 cells in individuals with an inverted CD4/CD8 ratio. When con sidered over the duration of the OCTO study the inversion occurred in a hig h percentage (32%) of the individuals included in the original sample and w as associated with non-survival. At T4 the changes were apparent in a numbe r of the T-cell subsets, but particularly in the CD8(+)CD28(-) and CD57(+) subsets. T-cell activation was significantly associated with the inversion of the CD4/CD8 ratio. In this very old sample the subset alterations were a ssociated with evidence of cytomegalovirus (CMV) infection. (C) 2000 Elsevi er Science Ireland Ltd. All rights reserved.