Innate and adaptive immunity in acute and chronic lung inflammation. A variety of host and environmental factors contribute to the development of acute and chronic lung inflammation. Recognition of pathogen associated molecular patterns (PAMPs) or endogenous damage associated molecular patterns (DAMPs) by host pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), elicits innate immune responses that subsequently instruct adaptive immunity. Recovery from the inciting stimulus depends on robust yet tightly regulated innate and adaptive immune responses. Deficient innate immune signaling leads to excess pathogen burden while an exaggerated response can cause severe tissue injury and death of the host.