Learning in a simple biological system: a pilot study of classical conditioning of human macrophages <it>in vitro</it>

Abstract

Abstract Recent advances in cell biology and gene regulation suggest mechanisms whereby associative learning could be performed by single cells. Therefore, we explored a model of classical conditioning in human macrophages in vitro. In macrophage cultures, bacterial lipopolysaccharide (LPS; unconditioned stimulus) was paired once with streptomycin (conditioned stimulus). Secretion of interleukin-6 (IL-6) was used as response measure. At evocation, conditioning was not observed. Levels of IL-6 were higher only in those cultures that had been exposed to LPS in the learning phase (p's However, habituation was evident, with a 62% loss of the IL-6 response after three LPS presentations (p

Keywords

• associative learning
• conditioning
• habituation
• <it>in vitro</it>
• monocyte
• macrophage
• lipopolysaccharide
• streptomycin
• interleukin-6