Alternative versus classical activation of macrophages

In parallel to the Th1/Th2 paradigm, antigen-presenting cells (APC) are div ided into classically activated APC (dendritic cells/effector macrophages) and alternatively activated APC (IL-4-induced, alternatively activated macr ophages/IL-10-induced, immature dendritic cells). Alternatively activated A PC share a special molecular repertoire including receptors of innate immun ity with broad specificity for foreign antigen and anti-inflammatory cytoki nes such as IL-1Ra and alternative macrophage activation-associated CC-chem okine-1. Alternatively activated APC mediated tolerance and downregulated i nflammation. Abuse of alternatively activated APC in support of infectious susceptibility or tumor immune escape is counteracted by the classical path way. Thus, classically and alternatively activated APC secure the balance b etween proinflammatory and anti-inflammatory immune reactions. Copyright (C ) 2000 S. Karger AG, Baser.