T-Lymphocyte interleukin 6 receptor binding in patients with dementia of Alzheimer type

Objective: To investigate some aspects of T-cell-dependent immune function in patients with dementia of the Alzheimer type (DAT). Design: Assay of interleukin 6 binding on T lymphocytes from patients with DAT, compared with that in healthy controls. Setting: The study included ambulatory patients in a tertiary care center who were diagnosed as having DAT according to the criteria of the National Institute of Neurologic and Communicative Disorders and Stroke. Subjects: Thirty-five patients with DAT without depression (15 women and 20 men; mean +/- SD age, 68.6 +/- 15.8 years) were selected consecutively. They had not taken any medication for at least 3 weeks and did not smoke. Illness severity was evaluated according to the Clinical Dementia Rating Scale. Thirty-five age- and sex-matched healthy nonsmoking subjects with no family history of neuropsychiatric disorders formed the control group. Results: A significant (P<.001) increase in T-lymphocyte interleukin 6 binding was found in patients with DAT compared with healthy controls (mean +/- SE receptors per cell, 305 +/- 7 vs 276 +/- 6, respectively), whereas the ligand-receptor affinity values were similar in the 2 groups (mean +/- SE, 25.9 +/- 0.9 and 25.3 +/- 0.6 nmol/L). Conclusion: These data indicate a derangement of the immune response in patients with DAT since cell-surface interleukin 6 receptors seem to be related to T-lymphocyte immune function.