This panel contains the following components:

• Absolute CD4⁺ helper T cells (CD3⁺CD4⁺)
• Absolute CD8⁺ cytotoxic T cells (CD3⁺CD8⁺)
• Absolute lymphocyte count
• Absolute T cells (CD3⁺)
• CD4⁺:CD8⁺ ratio
• Percentage and absolute natural killer (NK) cells
• CBC with differential and platelet count

This test evaluates several important types of T-lymphocytes which are critical immune response, CD4⁺, aka T helper cells, CD8⁺, aka cytotoxic T cells (note: does not measure suppressor cells as the old terminology name seems to imply) and natural killer cells. T-helper cells (CD4⁺) play a critical immune role by activating our B-cell antibody production in response to extracellular pathogens and activating our macrophages in response to intracellular pathogens. Cytotoxic cells (CD8⁺), on the other hand, are specialized T cells which can recognize and directly kill cells that are damaged or infected with intracellular pathogens without CD4⁺ activation. Cytotoxic T cells (CD8⁺ cells) are important in our daily battle against rogue cells that could potentially give rise to cancer cell and against viruses.

Both CD4⁺ and CD8⁺ cells are part of our adaptive immune system. While the adaptive immune system is very important and powerful, it can take a few days to respond to a new infection as several steps are required between pathogen recognition and antibody development/macrophage activation. Natural killer cells are part of our innate immune system, this means that they are on guard and ready to respond immediately to an incoming threat or precancerous cell.

CD4⁺, CD8⁺, and natural killer cells are types of T-lymphocytes that are necessary for healthy immune function and our ability to fend off microbial invaders such as virus, bacteria and parasites, as well as to clear cells that have undergone damage and pose a cancer risk. Testing the number of each of these cells can provide information on immune status and response and gives crucial information on key players in our innate (immediate) and adaptive (takes more time for activation) immune response.

This test also has a special application for monitoring HIV. HIV-1 infection results in a decrease of CD4⁺ T cells, an increase in CD8⁺ T cells, and thus a decrease in the CD4⁺:CD8⁺ ratio, equating to a progressive destruction of immune function. Enumeration of CD4⁺ and CD8⁺ T cells in HIV-1 seropositive patients may be used for prognostic purposes, to monitor disease progression and retroviral therapy.

Instructions

Fasting is not required for this test. Take all medications as prescribed. This test should be drawn Monday through Thursday only. It must arrive at the testing laboratory in less than 48 hours in order to preserve cell viability. Due to the limited viability of these cells, we cannot offer this test in a blood draw kit. The blood must be drawn at a LabCorp Patient Service Center or at the Life Extension Nutrition Center.

Note

The name of this test is based on older immunology nomenclature used by LabCorp (i.e. suppressor T cells). It is now known that CD8⁺ cells are primarily representative of the cytotoxic T cell population rather than the suppressor/regulator T cell population. Therefore, those who run this test should be aware that it is the cytotoxic cell population that is represented by the results, rather than the suppressor T cell population (aka T-reg population). LabCorp is investigating a name change to remove suppressor from the name of the test.