Immunoglobulins G and immunoglobulins M, also known as IgG and IgM, are antibodies that the body produces when it comes into contact with some type of invading microorganism. These antibodies are produced with the objective of promoting the elimination of bacteria, viruses, parasites and fungi, in addition to toxins produced by these microorganisms when they invade the body.
IgM is the first antibody to be produced when there is an infection, being considered a marker of the acute phase of the infection. IgG is produced a little later, but still in the acute phase of infection, but it is produced according to the invading microorganism, being considered more specific, in addition to 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, IgGs are a kind of memory that the organism creates for the rest of life.
Why is the exam done
The serological examination of IgG and IgM serves to detect the stage of several diseases, such as toxoplasmosis, rubella and infection by cytomegalovirus, for example. When a new infection occurs, the first antibodies produced are the IgM that decrease as the infection is controlled, giving rise to IgG, which remains for the rest of life.
| Negative IgG | Positive IgG | |
|---|---|---|
| Negative IgM |
The person never came into contact with the microorganism. |
The person came into contact with the microorganism in an old infection or was successful with the vaccine. |
| IgM positive |
The person has or has been with an acute infection for a few days. |
The person had a recent infection a few weeks or months ago. |
Thus, the existence of large amounts of IgM for rubella, for example, is a sign that the infection is recent, and when its levels drop, those of IgG remain, which means that the infection is controlled and the body is producing specific antibodies against this virus, thus obtaining immune memory for that disease.
Thus, in a close contact with the virus, the risk of developing the disease would be minimal, since the person would have specific IgG antibodies against rubella that would act immediately. The same happens with vaccination, in which, in most cases, inactive viruses are administered that induce the formation of specific IgGs.
Examination of IgG and IgM in pregnancy
During pregnancy, the doctor may perform some blood tests to identify the infections that the woman has had and to assess her immune status, by measuring specific antibodies for each of the infectious agents.
There are 5 infections that, if they remain in pregnancy, can have a high risk of transmission to the fetus, being even more serious when the mother without antibodies to one of these viruses, acquires the disease during pregnancy, as is the case of toxoplasmosis, syphilis, rubella, herpes simplex and cytomegalovirus. See how cytomegalovirus can affect your baby and pregnancy.
Thus, it is very important to have a rubella vaccination about a month before pregnancy, and to have a serological test in order to treat other infections in advance. See the consequences of rubella in pregnancy.
