This test measures CD4 cell concentrations in the blood. CD4 is a type of lymphocyte (white blood cells). They are an important part of the immune system. CD4 cells are sometimes called T-cells. There are two main types of T-cells. T-4 cells, also called CD4, are “helper” cells. They lead the attack against infections. T-8 cells (CD8) are “suppressor” cells that end the immune response. CD8 cells can also be “killer” cells that kill cancer cells and cells infected with a virus.
This test looks for antibodies to three diseases: measles, mumps, and rubella. The test can find out whether you are immune to the three diseases. All three are quite contagious. If you've had them or been vaccinated against them, your immune system made antibodies to fight the viruses that cause them.