Immunoglobulins G and immunoglobulins M, also known as IgG and IgM, are antibodies that the body produces when it comes in contact with some type of invasive microorganism. These antibodies are produced to promote the elimination of bacteria, viruses, parasites and fungi, as well as toxins produced by these microorganisms when they invade the body.
IgM is the first antibody to be produced when there is an infection and is considered an acute phase marker of infection. IgG is produced somewhat later but is still in the acute stage of infection, but is produced according to the invading microorganism, being considered more specific, besides remaining circulating in the blood, protecting the person against possible future infections by the same microorganism. Understand how the immune system works.
The production of IgG is also induced by vaccination in order to protect the body against a specific infectious agent. Thus, IgG are a kind of memory that the body creates for the rest of life.
Why is the exam done?
Serological testing of IgG and IgM is used to detect the stage of various diseases, such as toxoplasmosis, rubella and cytomegalovirus infection, for example. When a new infection occurs, the first antibodies produced are the IgM that decreases as the infection is controlled, giving rise to IgG, which remain for the rest of life.
| Negative IgG | Positive IgG | |
|---|---|---|
| IgM negative |
The person has never come into contact with the micro-organism. | The person came in contact with the micro-organism in an old infection or had success with the vaccine. |
| Positive IgM | The person has been or has been a few days with an acute infection. | The person has had a recent infection for weeks or months. |
Thus, the existence of large quantities of IgM for rubella, for example, is a sign that the infection is recent, and when their levels drop, IgG remains, meaning that the infection is controlled and the organism is producing specific antibodies against this virus, thus obtaining immune memory for this disease.
Thus, in close contact with the virus, the risk of developing the disease would be minimal because the person would have rubella-specific IgG antibodies that would act immediately. The same is true of vaccination, where, in most cases, inactivated viruses are given which induce the formation of specific IgGs.
IgG and IgM test in pregnancy
During pregnancy, the doctor may perform some blood tests to identify the infections the woman has already had and to assess her immune status by dosing specific antibodies for each of the infectious agents.
There are 5 infections that remain in pregnancy, may have a high risk of transmission to the fetus, and is even more serious when the mother without antibodies to one of these viruses, acquired the disease during pregnancy, as is the case of toxoplasmosis, syphilis, rubella, herpes simplex and cytomegalovirus. See how cytomegalovirus can affect the baby and pregnancy.
It is therefore very important to carry out the rubella vaccination about one month before the pregnancy, and to perform the serological test in order to treat the other infections in advance. See the consequences of rubella in pregnancy.
