Defensins are small proteins that play a crucial role in the immune system. They are produced by various cells in the body, including neutrophils, macrophages, and epithelial cells. Defensins help protect against infections by disrupting the membranes of bacteria, fungi, and some viruses, effectively neutralizing these pathogens. These proteins are categorized into three main types: alpha-defensins, beta-defensins, and theta-defensins. Each type has a unique structure and function, but all share the ability to combat microbial threats. Defensins are essential for maintaining the body's first line of defense and contribute to overall health and immunity.