What substance secreted by epithelial cells helps to control microbial growth?

Antimicrobial peptides are small proteins produced by epithelial cells that play a crucial role in the innate immune response. These peptides help control microbial growth by directly targeting bacteria, fungi, and viruses. They do this through several mechanisms, such as disrupting the microbial cell membrane, which leads to cell lysis and death. Additionally, antimicrobial peptides can enhance the immune response by attracting immune cells to sites of infection and promoting inflammation. This makes them essential for maintaining the integrity of epithelial barriers and providing rapid defense against pathogens.

By contrast, histamine, bradykinin, and prostaglandin are all involved in inflammatory responses but do not have the direct antimicrobial properties that antimicrobial peptides possess. Histamine is primarily involved in vasodilation and increasing blood flow to affected areas, while bradykinin is a peptide that contributes to pain and inflammation. Prostaglandins are lipid compounds that have various roles in the inflammatory response, including the modulation of pain and fever. However, none of these substances have the direct ability to inhibit or kill microbes as antimicrobial peptides do.