Host Defense Proteins of the Male Reproductive Tract

Abstract

Innate immunity, the rapidly responsive and phylogenetically ancient system of host defense, is generating increasing interest in part due to the growing appreciation for its remarkable broad spectrum effectiveness.We dwell in a sea of micropredators that are well equipped to colonize and invade our tissues.Yet we coexist with these organisms day after day without chronic inflammation, tissue damage, or even awareness of their presence.Coexistence occurs largely because the innate immune system, which includes antimicrobial proteins, complement, and phagocytes, prevents invasion by destroying or evicting the microbes.Only those maintaining commensal status are allowed to colonize.In addition, evidence is emerging to indicate that antimicrobial proteins stimulate the adaptive immune response.When the innate immune system is overwhelmed and tissue invasion does occur, the T lymphocytes and antibody-producing B lymphocytes of the adaptive system are recruited to eliminate the infection.The success of plants, insects, and other lower animals that lack adaptive immunity affirms the effectiveness of the innate immune system.Today, more than 700 antimicrobial proteins are known in the plant and animal kingdoms.The Antimicrobial Sequences Database lists 752 eukaryotic entries as of February 12, 2002(Tossi et al, 2002); this is a dramatic increase since the original discoveries in plants 30 years ago (Fernandez-de-Caleya et al, 1972), and in animals 20 years ago (Hultmark et al, 1980;Steiner et al, 1981;Selsted et al, 1983).Through improved understanding of innate antimicrobial proteins, ways to mimic or enhance their activities