T Lymphocyte Subpopulations and Activation Markers Correlate with Severity of Alzheimer's Disease
In this study we investigated immune-associated antigens of peripheral lymphocytes from patients with Alzheimer's disease (AD). The patients were divided into two groups—mild and moderately severe—according to severity of disease stage, and their lymphocytes were compared to those of elderly controls. In the mild stage of the disease we observed a slight increase in the HLA-DR marker (9.5 ± 2.4% vs 6.5 ± 1.1%; P = 0.06), but no changes in the CD4, CD8, and interleukin-2 receptor (IL-2R) markers. In the moderately severe stage, we observed a significant increase in the HLA-DR (18.5 ± 2.7%) and CD4 markers (55.2 ± 3.5% vs 43.5 ± 2.1%, P < 0.01), and a slight decrease in the CD8 subset 119.5 ± 1.4% vs 22.3 ± 1.3%, P = 0.05). In the same group, following stimulation with the mitogen PHA, we observed a marked reduction in IL-2R expression (30.9 ± 4.7% vs 41.1 ± 2.7%, P = 0.05) and in the proliferative ability of lymphocytes 121131 ± 4676 cpm vs 47909 ± 1107 cpm, P < 0.04). However, mitogen-induced IL-2 secretion levels from the same lymphocytes were significantly elevated 117.4 ± 4.8 U/ml vs 8.6 ± 4.3 U/ml, P < 0.01). Marked changes in immunological parameters in the moderately severe group support the hypothesis of a peripheral immune reaction in AD which may be correlated with the clinical stage of the disease.