Abnormal erythrocyte anion exchange in Alzheimer disease.

Abstract

Several abnormalities have been described in red blood cells of patients with Alzheimer disease (AD), but to date none of these has been confirmed by a second, independent study. Erythrocyte anion exchange has been reported to be abnormal in AD; we have developed a new technique for measuring anion exchange. To confirm the abnormality of erythrocyte anion exchange in AD and to determine whether the phenomenon has potential for clinical utility. Comparison of patients with probable AD to age-matched controls. University hospital and ambulatory clinic. Chloride-bicarbonate exchange was measured in erythrocyte ghosts resealed with a fluorescent probe of chloride concentration. Erythrocyte anion exchange is abnormal in AD. This difference appears in citrate but not EDTA anticoagulant. Mahalanobis's generalized distance between the 2 populations is 1.7, and a discriminant function derived from our technique classifies 82% of the study population in accordance with the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria. Receiver operating characteristic analysis demonstrates the possibility of choosing cutoffs with high sensitivity and specificity. Measurement of red blood cell anion exchange may be useful in classifying patients with AD. The dependence of this phenomenon on anticoagulant suggests the involvement of platelet activation or complement fixation.