Innate immunity is a first line of host defense against pathogens, it plays a key role in the activation of adaptive immunity and in the maintenance of tissue repair. Recognition of pathogens and damaged tissues is mediated by pattern recognition receptors (PRRs) that are part of both the cellular and humoral arms of innate defense mechanisms. Toll-like receptors (TLRs), scavenger receptors, and lectin receptors are cellular PRRs, whereas the humoral arm of innate immunity includes collectins (mannose-binding lectin, surfactant proteins A and D, C1q), ficolins, and pentraxins.