An IgM antibody, or an immunoglobulin M antibody, is one of the five types of antibodies the body produces in response to invading antigens. Antibodies are proteins found in body fluids, such as blood and saliva, which help the immune system fight off infection. They are always specific, which means, that for each type of antigen a corresponding specific antibody is also produced. Antigens are substances that are considered foreign to the body and whose presence often trigger the production of antibodies. Examples of antigens are viruses, fungi, parasites, and bacteria.
In an individual with a healthy immune system, the invasion of an antigen could set off a chain of events to fight off the attack. As bacteria or viruses enter the body, the white blood cells (WBC) often identify these organisms as foreign to the body. They in turn activate the plasma cells, another type of WBC, which are mostly responsible in antibody production. These plasma cells produce the IgM antibody. Other types of antibodies produced by plasma cells are immunoglobulin E (IgE) antibody, Immunoglobulin G (IgG) antibody, Immunoglobulin A (IgA) antibody and Immunoglobulin D (IgD) antibody.
Each antibody type has certain actions and locations in the body. The IgM antibody is the largest of the antibodies and found mostly in the lymph fluid and the blood. It is generally responsible for neutralizing antigen invasion during the early stage of the disease, until enough IgG antibodies are produced. The second time the same antigen attacks the body, these specific IgG antibodies will be the ones to neutralize them. IgM antibody is often referred to as the first line of defense and its presence in the blood is often indicative of an infection.
IgG antibodies are the most abundant and smallest antibodies and they are mostly present in body fluids. IgE antibodies are found in the mucous membranes, lungs, and skin, and are often present in elevated amounts in the blood of individuals with allergies. IgA antibodies are located in many body surfaces such as the nose, vagina, and eyes, and are responsible in protecting these exposed areas to foreign substances. IgD antibodies are frequently found in small amounts in some body tissues.
A healthy immune system is often capable of producing IgM antibody as well as the other types of antibodies during infection. Some factors, however, may potentially weaken the immune system, making the person more susceptible to infections and other diseases. These factors include excessive intake of sugar-containing foods, oxygen depletion in the body, and side effects of certain treatment procedures such as chemotherapy. Individuals with weak immune systems are considered immunocompromised, and they can easily catch viral conditions like flu which a healthy person could easily ward off.