Lymphocyte Proliferation Assay (Stimulated by Phytohemagglutinin)

This test measures how well a type of white blood cell called a lymphocyte can grow and multiply when it is exposed to specific substances in the laboratory, giving your care team a picture of how strongly your immune system can respond to challenges such as infections.

The test evaluates the ability of your lymphocytes to divide and multiply in response to a specific stimulus (phytohemagglutinin, or PHA). Normally, healthy lymphocytes will proliferate when exposed to this antigen, indicating a functional immune response.

A small blood sample is drawn from a vein in your arm. In the laboratory, the lymphocytes are separated from the sample and exposed to a stimulating substance, such as an antigen or a plant compound. The lab then measures how much the cells divide and grow, usually after several days of incubation.

A small sample of your blood is taken and exposed to PHA. After a set period, the number of dividing lymphocytes is measured to determine how effectively your immune cells are responding.

Doctors use this test to check how well your cell-mediated immunity is working. It can help diagnose weakened immune function, investigate frequent, unusual, or long-lasting infections, evaluate suspected immune deficiencies, and monitor treatments or medications that suppress the immune system.

This test may be recommended if you have symptoms of immune dysfunction, such as frequent infections, unexplained fatigue, or if you’re being evaluated for conditions like HIV, lupus, or other autoimmune disorders.

Preparation is usually simple. Tell your doctor about every medicine and supplement you take, especially corticosteroids, chemotherapy, or other immunosuppressive drugs, because these can change the results. You may be asked to avoid eating beforehand only if other blood tests are ordered at the same time. The sample is collected with a standard blood draw, which takes only a few minutes.

No special preparation is needed, but you may be asked to avoid certain medications that could affect immune function, such as steroids. Bring any recent medications to your healthcare provider’s office.