Adaptive characteristics of innate immune responses in macrophages

Abstract

Macrophages are a central component of antimicrobial host defense, described as crucial for both innate immune mechanisms and adaptive immunity (Gordon and Mantovani 2011). The dichotomy between the immediate antimicrobial responses seen as non-specific, and the late-onset specific T- and B-cell responses, has been driven our understanding of host defense for more than half a century. Innate immunity reacts instantly upon an encounter with a pathogen, but has been viewed as non-specific and incapable of building an immunological memory. In contrast, adaptive immune responses can specifically recognize pathogenic microorganisms and build memory capable of protection against reinfection. Macrophages are involved in both these two responses: on the one hand macrophages have the capacity to phagocytose and kill microorganisms in a non-specific fashion, to release proinflammatory mediators that drive inflammation, but on the other hand they can also present antigens and initiate and modulate the specific T-cell responses through expression of co-stimulatory molecules and specific cytokines (Taylor et al. 2005).