Your immune system is made up of proteins, cells and organs that all work together to help keep your body safe from invasion by pathogenic organisms, like infectious bacteria and viruses. There are a number of proteins that the immune system depends upon in order to maintain normal function.
IgG Antibodies
Of all the immune system proteins, IgG antibodies are the most well-known in the general population. These are antibodies that circulate in your bloodstream and provide the vast majority of your defense against invading bacteria and viruses. They do this in more than one way, explains Dr. Lauralee Sherwood in her book "Human Physiology"; for instance, they can clump pathogens together, making removal easy, or can mark pathogens for destruction. They also cross the placenta, giving a new baby a short period of immunity until he begins to build his own immune system.
Other Antibodies
There are many other classes of antibodies, each of which is also important to normal immune function. IgA, for instance, lines the mucous membranes of your digestive tract and helps protect you from ingested pathogens. Babies get this type of antibody in breast milk, which is one of the reasons it helps protect them from disease. IgE protects mainly against parasites, such as worms. IgM has roles in early immunity, such as when you're first exposed to a pathogen and before you've had time to produce IgG.
MHC
The MHCs, or major histocompatibility complexes, are another group of proteins critical to immune cell function. These are proteins that your cells make and express onto the cell surface; they allow your immune system to monitor what's going on inside the cell, and provide an "early detection system" if the cell has been taken over by a pathogenic invader. Other immune cell components regularly check the MHCs on cell surfaces in order to monitor cell health.
CD3
A T-cell coreceptor called the CD3 receptor is a protein that has recently received some attention in the media because it's not only an important immune protein but also appears to have a role in brain development, explains Science Daily. While the immune system normally monitors for invading pathogens, some elements of the immune system, including CD3, appear to monitor the brain for incorrect connections between neurons, which helps the brain function more efficiently.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- ScienceDaily; Immune Proteins Play Role in Brain Development and Remodeling...; December 18, 2000
