Uptake - Immunological Principles of Vaccines

Uptake

Every immune reaction against a pathogen starts with its uptake by specialized phagocytic cells in the infected tissue. These cells carry receptors on their surface; pattern-recognition receptors (PRRs) that recognize common features of pathogens called pathogen associated molecular patterns (PAMPs). Binding of PAMPs to these PRRs results in phagocy-tosis of the pathogens. Examples of PRRs are toll-like receptors (TLRs), scavenger receptors and C-type lectins (Table 2). TLRs consist of a family of receptors, with each member recognizing different patterns on the surface of pathogens ( Akira et al., 2006). TLRs canbe found on many cells including macrophages and dendritic cells (DCs). DCs can also engulf materials from their extracellular environment by a receptor independent process called micropinocytosis.