T-Cell interferon gamma binding in patients with dementia of the Alzheimer type

Objective: To study T-cell-dependent immune function in patients with dementia of the Alzheimer type (DAT). Design: Assay interferon gamma binding on T lymphocytes in patients with DAT, as compared with healthy controls. Setting: The study was performed on ambulatory patients in a tertiary care center, where patients were diagnosed as having DAT according to the National Institute of Neurological Disorders and Stroke criteria. Patients: Thirty-five nondepressed patients with DAT (15 women and 20 men; mean [+/-SD] age, 68.6+/-15.8 years) were selected consecutively. They were drug free for at least 3 weeks and did not smoke. Illness severity was evaluated according to the Clinical Dementia Rating Scale. The control group comprised 35 age- and sex-matched, healthy, nonsmoking subjects; with no family history of neuropsychiatric disorders. Results: A significant reduction (P<.001) of T-lymphocyte interferon gamma binding was observed in patients with DAT as compared with healthy controls (611+/-19 [SE] vs 702+/-11 [SE] receptors per cell, respectively), whereas the dissociation constant (ligand-receptor affinity) values were similar in the 2 groups (1.1+/-0.06 [SE] and 1.2+/-0.06 [SE] nmol/L). Conclusion: These data demonstrate a derangement of the immune response in patients with DAT, since cell surface interferon gamma receptors seem to be related with T-lymphocyte immune function.