ABSTRACT
This chapter focuses on barriers to infection, pattern recognition receptors (PRRs), chemokines, complement, and cytokines and their function in mediating innate immune responses. Dysregulation or malfunction of the innate immune responses can lead to disease. The innate immune system functions to mediate the destruction of microbes, activation of phagocytosis, and local protective responses called inflammation and trigger tissue repair. The innate immune system cells express a large family of PRRs including Toll-like receptors that can recognise the evolutionarily conserved structures on pathogens called pathogen-associated molecular patterns, which can be proteins, lipids, sugars, nucleic acids, or conjugated moieties of macromolecules. The complement system functions as an integral part of the innate immune response and acts as a bridge between innate and acquired immunity. The innate immune system involves a group of proteins and phagocytic cells that recognise conserved features of pathogens and become quickly activated to help destroy invaders.
