What are Immune Labs?

Immune labs are blood tests that check how your child’s immune system is working. These tests look at things like antibodies and certain types of blood cells to see how the body fights germs and responds to vaccines.

What Is an Immunoglobulin?

Immunoglobulin is another word for antibody. Antibodies help your child’s body remember germs. If those germs come back, their body can fight them off faster and stronger.

What is an Antibody Blood Test?

An antibody blood test checks your child’s blood for certain antibodies the immune system makes after it meets a virus, germ, allergen or vaccine. This test shows whether the immune system has seen something before and how it responded.

Healthcare providers at Children’s Wisconsin use this test to see how much of each antibody type is in your child’s blood. They look at whether the antibody levels are higher or lower than what is expected. This helps them understand how your child’s immune system is working and whether it is responding the way it should.

The 4 Main Types of Antibodies in the Blood

• IgM. IgM is the first kind of antibody the body learns to make. It is also the first one to increase when your child gets sick. IgM levels can go up or down depending on whether there is an infection.
• IgA. IgA is found in places that make mucus, like the eyes, nose, lungs, and gut. It helps protect these areas from infection. IgA is the antibody people are most likely to have low or missing. A low IgA level by itself is usually not a problem.
• IgG. IgG is the main antibody the body uses to fight infections. It also helps the body “remember” germs after an illness or vaccine, which gives long term protection. When IgG levels are low, a child may get infections more easily. Some medicines can lower IgG as a side effect.
• IgE. IgE is the antibody linked to allergies and skin problems like eczema. IgE levels can be high when allergies or eczema are active. A low IgE level by itself is not a concern.

What Is a Vaccine Titer?

A vaccine titer is a blood test that shows how well your child’s body remembers a vaccine. It helps healthcare providers see if the vaccine worked the way it should. Titer levels show if your child’s body remembers a vaccine and can fight the germ well if it comes back.

Types of Vaccine Titers Your Child May Have Checked

Tetanus
Tetanus is a routine vaccine that most people receive. The body usually responds to it very well, so it is often used to check how the immune system is working.

Hib (Haemophilus influenzae type b)
Hib is a vaccine that protects against a germ called Haemophilus influenzae. This germ can cause ear and sinus infections, and more serious illnesses. Most children receive 3 to 4 doses as part of their regular vaccine schedule.

Pneumococcal
The pneumococcal vaccine protects against a germ called Streptococcus pneumoniae. This germ can cause pneumonia (a lung infection), as well as sinus and ear infections. There are 2 main types of pneumococcal vaccines. Each one protects against many different strains of this germ. Children usually get a series of 3 doses as part of the routine vaccine schedule. Since the vaccine protects against so many strains, it is normal for only about a half of the titer levels to fall within the expected range.

What Happens if the Titer Level is Low?

If the titer level is low, your child may need a booster shot. A booster shot helps remind the immune system how to fight the germ. If your child’s immune system is working normally, it should respond to the booster in about 4 weeks. After that, the provider will check your child’s blood again to see the new titer level and make sure the booster worked.

Other Tests

The provider may also order other tests that check other parts of the immune system.

To learn more about vaccines review this Children’s Wisconsin Resource.

To learn more about immunoglobulin review this KidsHealth Resource.