Cytokines in Alzheimer's disease.

1. Human astrocytoma cells produced biologically active interleukin-6 when treated with a variety of agents including bacterial lipopolysaccharides, viruses, and interleukin-1. 2. Both human recombinant IL-6 and IL-6 produced by stimulated astrocytes promoted differentiation of cultured neuronal cells and reduced survival time in culture. 3. Interleukin-6 and interleukin-1 stimulated the synthesis of the Alzheimer's disease beta-amyloid precursor protein. 4. Cytokines may be involved in stimulation of dystrophic neuritic sprouting, neuronal death, and amyloid deposition noted in the brains of Alzheimer's disease patients.