What Are the Best Lab Tests for Immune System Function and what They Indicate

Page content

Complete Blood Count

A complete blood count can give your doctor a good indication of how your immune system is functioning. Your immune system protects you from infections and disease-causing organisms as well as any foreign materials which may enter your body.

Your body contains five different types of white blood cells which respond to stresses on your immune system. A review of the number and types of white blood cells found in a sample can provide information regarding the presence of a disease. Your doctor will use a range to determine if your complete blood count is normal. If your numbers fall outside of this range, she can make an assessment about how your immune system is functioning.

For example, a high neutrophil count might indicate that you have a bacterial infection. In this case, your immune system is responding properly. A high eosinophil count can result from an autoimmune disorder which would show that your immune system is responding inappropriately to some type of stimulus.

Your doctor may also look at the lymphocyte percentage in your blood. Lymphocytes make antibodies and attack germs, depending upon the type. Again, your doctor will use a range to determine if your sample is normal. Your lymphocytes should make up between 20 and 40 percent of your entire white blood cell count.

Immunoglobulin Tests

A measurement of quantitative immunoglobulin levels in the blood serum gives your doctor a summary of your body’s immunoglobulin function. Immunoglobulins are antibodies synthesized by your body’s plasma cells. Abnormalities in immunoglobulin levels can indicate specific problems with your immune system.

Your doctor will likely order a test for gliadin IgG and gliadin IgA if you are showing symptoms of gluten intolerance or celiac disease such as gastrointestinal distress and weight loss. When these immunoglobulins are detected in your blood, it means that your body is fighting some foreign material in your body. In this case, your body is attacking the cells of your small intestine in response to the present of gluten in your diet.

Complement Assay

What are the best lab tests for immune system function? The complement assay looks at the activity of your nine major complement proteins as an indication of immune function. Your doctor can also perform specific protein tests to determine the presence of disease.

Like a complete blood count, abnormalities in protein levels can be diagnostic. For example, your doctor may order a test for the C3 and C4 proteins if you are experiencing symptoms of lupus erythematosus such as the classic butterfly skin rash on your cheeks or joint pain. It may also be used to monitor your pre-existing condition.

A determination of what are the best lab tests for immune system function depends upon your symptoms as well as your medical and family history. In any case, a simple blood test is a non-invasive way for your doctor to accurately diagnose and begin treatment for health conditions.


National Institutes of Health: Complement – nlm.nih.gov

Tortora, G. and Grabowski, S. Reynolds. Principles of Anatomy and Physiology. 1996