Immune functional tests are used to assess how well the cells involved in defence against infections respond to some stimuli.
There are basically two types of primary immunodeficiencies: humoral and cellular (or both at the same time). In humoral immunodeficiencies there is a decrease of immunoglobulins. In cellular immunodeficiencies there is a malfunction of the cells (leukocytes/white blood cells) that respond to microorganisms and foreign invaders.
In immune tests, the cells can be counted to check if their number is in the normal range. To assess their function, the cells are incubated with some chemical compounds to see how they proliferate, express defence proteins or release mediators.
For some immunodeficiencies, genetic studies are available instead of functional tests.
Immune functional tests are laborious, and are not available in most of the hospitals. Instead, the tests are performed in reference centres with more resources and experience.
The tests require a blood sample. No specific preparation is needed if you are scheduled for immune functional test. Nevertheless you should inform your doctors about all the medications that you are receiving. Sometimes they will ask for a relative without immunodeficiency to undergo the same tests to compare results with that of the patient.