Immunology 101

Immunology 101

Most of us understand that maintaining a healthy immune system is important to our overall health and well-being. However, the immune system is one of the most complex and least understood systems of the human body.

The immune system defends humans and animals from infections caused by pathogens such as bacteria, viruses and fungi. The immune system can be broadly segregated into two parts: innate immune system and the adaptive immune system (Figure 1). The ‘innate’ (meaning: “present from birth”) part of the immune system is so-called because it has a number of set strategies for recognizing and destroying infections, without needing to be trained to identify them. The adaptive immune system isn’t able to respond instantly to infections, as it needs time to adapt (or learn) to recognize them. Once it has learned, however, it is extremely effective and is also able to remember particular pathogens that have previously infected the body, so that when (or if) they try to infect the body again, the next response is rapid, accurate, and effective. This concept is the basis for vaccinations most of us receive when young to prevent infection from certain pathogens.

The adaptive immune system is composed of lymphocyte cells (B and T cells) that can learn to identify pathogens and provide with a specific response to kill the pathogen. Adaptive immune cells produce soluble factors, such as antibodies, which neutralize the ability of pathogens to infect the host and antibodies also enhance the antimicrobial activities of phagocytes. The ability to produce antibodies to kill a specific pathogen is a learned or memory response and takes years to fully develop.

Innate Immunity
The innate immune system is composed of phagocytic cells that engulf (eat) pathogens, other immune cells that release chemicals (oxidative burst) to kill pathogens and soluble factors, such as complement, which have antibacterial properties on their own and identify pathogenic cells for attack. Generally, innate immune cells migrate to sites of infection via the bloodstream, following the trail of complement to the site of infection, and neutralizing the pathogens by engulfing them and killing them.

Innate immune cells kill pathogens and infected host cells by two interrelated methods, phagocytosis or oxidative burst. If the target cell is small enough, the phagocyte will engulf the target, bringing it completely inside the immune cell. Once the target is inside, the phagocyte will release highly reactive oxygen compounds (oxygen superoxide, hydrogen peroxide etc.) and other microbiocidal agents, which kills the pathogen and very often the phagocytic cell. If the target is too large to be engulfed by the phagocyte, these same reactive agents are released outside the phagocyte in a process called oxidative burst. In addition to killing the target, oxidative burst will often kill or damage both the phagocytic cell and surrounding host tissue.

Wellmune binds to special receptors on neutrophils that evolved to detect yeast and fungal infections. Once primed by Wellmune, neutrophils respond more efficiently to signals from the immune system. Click here for more information about how Wellmune works in the body.