Antimicrobial peptides and proteins in human biological fluids

Antimicrobial peptides and proteins (AMPs) are endogenous compounds that have a direct antimicrobial effect on bacteria (e.g. by disrupting bacterial membranes) as well as on fungi and viruses. AMPs are the main components of the innate immunity of living organisms and are produced by both epithelial cells (skin cells, cells of respiratory tract, intestines, urinary and genital tracts) and cells of the immune system and are secreted into secretory fluids. AMPs can also act as chemoattractants for immunocompetent cells (neutrophils, monocytes, T lymphocytes, dendritic cells) in the inflammation site and affect the antigen presenting cells by modulating adaptive T cell immune responses. The representatives of the main 15 AMP classes, that we describe in this review, are the most studied group of the large pool of these compounds. We discuss their localization, expression, and concentration in various human biofluids under normal and pathological conditions