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Differences Between IGG & IGM

An immunoglobulin, also known as an antibody, is a protein that fights against disease by binding to antigens. Antibodies are produced by the immune system and respond to specific threats within the body. Both IgM and IgG are antibodies, but they are produced very differently, have different effects, and solve different problems.

  1. Initial Response

    • IgM is produced by the immune system once it is exposed to bacteria or toxins. It is the body's first line of defense against disease, and works by binding to antigens immediately. IgM is a temporary antibody, and it will disappear from the body after a few weeks, once a short term threat has been handled. However, the human body is constantly producing new sources of IgM to fight new external threats.

    Long Term Immunity

    • IgG is produced by the immune system to handle bacteria, viruses and toxins long term. The IgG antibodies replace the IgM antibodies after a few weeks. They are responsible for long term immunity to certain diseases. For instance, if a child gets chicken pox, their body will produce IgM at first to battle the bacteria. After this process is complete, IgG will replace the IgM antibodies and maintain long term immunity to chicken pox.

    Location In the Body

    • IgM is found primarily in the blood stream and lymph fluid, where it can effectively fight exposures to disease. IgM may, however, be found in other bodily fluids in other parts of the body. IgG, since it fights long term immunity, is found in all parts of the human body, and in all bodily fluids. It is one of the most abundant proteins in the human body.

    Size

    • One of the main differences between IgG and IgM is that IgM is much larger in size, about six times larger than IgG. The reason for this is that IgM needs multiple sites on it with which to bind antigens. This gives it the greatest chance for fighting the acute effects of disease in its earliest stages. IgG does not require these multiple binding sites, since it is specifically produced to fight a certain kind of antigen which it targets.

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