Innate Immunity
The body's first line of defence against pathogens, comprising physical barriers, antimicrobial peptides, complement proteins, and immune cells that respond rapidly and non-specifically. Natural antimicrobial peptides (defensins, cathelicidins) are key components of innate immunity.
Technical Context
Innate immune components: physical barriers (skin, mucosal surfaces — including antimicrobial peptides such as defensins and cathelicidins), cellular defences (neutrophils — first responders, phagocytosis; macrophages — phagocytosis, antigen presentation, cytokine production; dendritic cells — antigen presentation, linking innate and adaptive immunity; NK cells — killing virus-infected and tumour cells; mast cells — histamine release, parasite defence; eosinophils — parasite defence), humoral defences (complement system — opsonisation, MAC formation, inflammation; acute phase proteins — CRP, mannose-binding lectin; interferons — antiviral state), and pattern recognition receptors (TLRs, NLRs, RLRs — detecting pathogen-associated molecular patterns/PAMPs and damage-associated molecular patterns/DAMPs). Antimicrobial peptides bridge innate and adaptive immunity — defensins recruit dendritic cells and T cells, while LL-37 promotes dendritic cell maturation.