CIRCULATING IMMUNE-COMPLEXES IN SERA FROM PATIENTS WITH ALZHEIMERS-DISEASE AND SUBJECTS WITH AGE-ASSOCIATED MEMORY IMPAIRMENT

Before, we reported a higher frequency of circulating immune complexes (CIC) in the sera from institutionalized Alzheimer's disease (AD), mu lti-infarct dementia and Down's syndrome patients than from age-matche d controls. In this study, we tested the presence of CIC in the sera f rom an extended series of hospitalized AD patients, AD patients living in the community, from age-associated memory impairment (AAMI) subjec ts as well as from nursing home and community controls. We used two me thods to measure CIC, Clq binding Elisa (ClqB-Elisa) and conglutinin b inding (KgB-Elisa). The AD patients showed the highest frequency of po sitive findings and differed from the controls in KgB (42% vs. 17%) (C hi-square, p = 0.01) and ClqB (30% vs. 11%) (p < 0.05). In severe AD, 14/19 patients were KgB positive and 11/19 were ClqB positive and diff ered from controls. The frequency of CIC for the patients with moderat e or mild dementia, the AAMI subjects and controls was similar. In the multivariate linear regression analysis, high CIC values of the AD pa tients significantly associated with a long disease duration and a his tory of recurrent urinary infections but not with age, sex, hospitaliz ation, or the Mini-Mental Status score. We conclude that AD patients w ith severe dementia frequently show CIC but those with mild or moderat e disease do not. The CIC relate to a long disease duration and a hist ory of recurrent urinary infections.