How Important Is Your CD4/CD8 Ratio? (2024)

T cells are a type of white blood cell that is central to your immune defense. There are four types which serve different functions:

  • CD8 T cells are considered "killers" because their function is to destroy any cells in the body that harbor a virus, bacteria, or other disease-causing agents (pathogens).
  • CD4 T cells are considered "helpers" because they start up the immune response.
  • Suppressor T cells are responsible for turning off the immune response when a threat has been neutralized.
  • Memory T cells remain on guard once a threat has been neutralized and "sound off the alarm" if the threat ever returns.

The CD4/CD8 ratio is one of the blood tests used to monitor your immune system if you have human immunodeficiency virus (HIV). It compares the proportion of so-called "helper" CD4 T cells to "killer" CD8 T cells, the value of which can help predict the likely course of the disease.

This article will guide you through how CD4 and CD8 cells interact, what the CD4/CD8 ratio tells us, some conditions in which the ratio can be either high or low, and how often you may need to be tested to monitor an illness.

How Important Is Your CD4/CD8 Ratio? (1)

How CD4 and CD8 T Cells Interact

CD4 and CD8 are simply two different types of glycoprotein found on the surface of T cells and other lymphocytes (the class of white blood cells central to the immune system).

CD4 T cells work by triggering an immune response when faced with a pathogen. CD8 T cells respond by attacking the tagged pathogen and neutralizing it. Suppressor T cells then "turn off" CD4 activity when a sufficient immune response has been achieved.

What is a normal CD4/CD8 ratio?

A CD4/CD8 ratio is considered normal when the value is between 1.0 and 4.0. In a healthy individual, that translates to roughly 30%–60% CD4 T cells in relationship to 10%–30% CD8 T cells.

When a person is first infected with HIV, there is generally a 30% drop in the number of CD4 T cells as HIV targets these cells and depletes their numbers. By contrast, CD8 T cells will generally increase by about 40%, although their ability to neutralize the virus will wane over time as there are simply fewer CD4 T cells to trigger an effective response. The CD4/CD8 ratio tends to decrease as we age, making people more susceptible to pathogens.

When HIV therapy is initiated promptly, the ratio will generally return to normal. However, if the treatment is delayed until the immune system is seriously damaged, the body's ability to create new CD4 T cells will weaken. If this happens, the ratio may never rise much above 1.0.

What the CD4/CD8 Ratio Tells Us

The prognostic (predictive) value of CD4/CD8 is considered less relevant to the management of HIV than it was 20 years ago. Back then, there were fewer, less effective drugs available to treat HIV. While the value can still help us determine the age of the infection and yourrisk of mortality, changes have been made in recent years.

There is now greater emphasis placed on sustaining viral control (as measured by anundetectable viral load).Doing so helps slow disease progression and avoids the development ofdrug resistance.

With that being said, increasing focus has been placed on the use of the CD4/CD8 ratio in people with long-term HIV infection, Recent studies have suggested that people with a low CD4/CD8 ratio who have been on treatment for years are at an increased risk of non-HIV-related illness and death.

There are several other areas in which the CD4/CD8 ratio may also be important. In epidemiological research, the ratio can be used to measure virulence (the ability to cause disease) of HIV in different populations or over specific periods.

It can also be used to predict the likelihood of immune reconstitution inflammatory syndrome (IRIS), a serious reaction that can sometimes occur when a person starts HIV therapy. If the baseline CD4 count is low and is accompanied by a CD4/CD8 ratio below 0.20, the risk of IRIS increases significantly.

Similarly, research has shown that a low CD4/CD8 count in babies born to HIV-positive mothers can be used to predict whether that baby will seroconvert (become HIV-positive too). The likelihood of this increases dramatically when the ratio falls below 1.0. This is especially relevant in developing countries where the rate of mother-to-child transmissions has dropped but the number of postnatal seroconversions remains high.

The CD4/CD8 ratio test is most frequently used to monitor HIV status. However, it can also be used to diagnose and assess other conditions.

Which Health Conditions Have a Low CD4/CD8 Ratio?

Aside from in HIV/AIDS, the CD4/CD8 ratio can be low in conditions including:

  • Infectious mononucleosis
  • Bone marrow problems related to chemotherapy
  • Anemia
  • Chronic lymphocytic leukemia
  • Hodgkin disease (lymphoma)
  • Multiple sclerosis, myasthenia gravis, or another nervous system condition
  • DiGeorge syndrome
  • Organ transplantation

Which Health Conditions Have a High CD4/CD8 Ratio?

The CD4/CD8 ratio can be high in conditions including:

  • Major infection
  • Viral infection
  • Type of blood cancer

How Often to Get Tested

For people newly diagnosed with HIV, routine blood monitoring should be performed at the time of entry into care and then every three to six months afterward. This includes the CD4 count and viral load. Once you have been on treatment and have maintained an undetectable viral load for a least two years:

  • CD4 monitoring can be performed every 12 months for people whose CD4 count is between 300 and 500.
  • CD4 monitoring may be considered optional for those with CD4 counts over 500.


The CD4/CD8 ratio is a blood test used to monitor the immune systems of people with HIV and other disorders. CD4 and CD8 cells react correspondingly to each other and their ratio (whether low or high) can indicate certain illnesses like HIV, multiple sclerosis, or blood cancer. CD4/CD8 ratio testing is typically done regularly, from the first sign of an illness, to monitor immune response.

7 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Okoye AA, Picker LJ. CD4(+) T-cell depletion in HIV infection: mechanisms of immunological failure. Immunol Rev. 2013;254(1):54-64. doi:10.1111/imr.12066

  2. Eisinger RW, Dieffenbach CW, Fauci AS. HIV Viral Load and Transmissibility of HIV Infection: Undetectable Equals Untransmittable. JAMA. 2019;321(5):451-452.doi:10.1001/jama.2018.21167

  3. Seng R, Goujard C, Krastinova E, et al. Influence of lifelong cumulative HIV viremia on long-term recovery of CD4+ cell count and CD4+/CD8+ ratio among patients on combination antiretroviral therapy. AIDS. 2015;29(5):595-607. doi:10.1097/QAD.0000000000000571

  4. Li CX, Li YY, He LP, et al. The predictive role of CD4+ cell count and CD4/CD8 ratio in immune reconstitution outcome among HIV/AIDS patients receiving antiretroviral therapy: an eight-year observation in China. BMC Immunol. 2019;20(1):31. Published 2019 Aug 28. doi:10.1186/s12865-019-0311-2

  5. Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection.

  6. MedlinePlus. CD4 Lymphocyte Count.

  7. OSF Healthcare. Tests & Procedures - CD4-CD8 Ratio.

Additional Reading

How Important Is Your CD4/CD8 Ratio? (2)

Dr. Sifris is an HIV specialist and Medical Director of LifeSense Disease Management. Myhre is a journalist and HIV educator.

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How Important Is Your CD4/CD8 Ratio? (2024)


How Important Is Your CD4/CD8 Ratio? ›

A normal CD4/CD8 ratio is greater than 1.0, with CD4 lymphocytes ranging from 500 to 1200/mm 3 and CD8 lymphocytes ranging from 150 to 1000/mm 3. If your ratio is higher than 1, it means your immune system is strong and you may not have HIV. If your ratio is less than 1, you may have: HIV.

Why is the CD4:CD8 ratio important? ›

The CD4/CD8 ratio is a reflection of immune system health. CD4 cells (also known as CD4 lymphocytes or T-helper cells) help coordinate the immune response by stimulating other immune cells, such as macrophages, B lymphocytes (B cells), and CD8 cells to fight infection. Untreated HIV targets and destroys CD4 cells.

What is a good CD4:CD8 ratio profile? ›

A CD4:CD8 ratio of more than 1.0 is considered normal. A CD4 count below 200 per cubic millimeters shows that you have acquired immunodeficiency syndrome (AIDS). Low CD4 counts are also seen in bone marrow suppression because of chemotherapy, long-standing infections, and some types of anemia.

What autoimmune disease has a high CD4:CD8 ratio? ›

Since 1980 it has been recognized that the proportion and number of CD8+ T cells in the peripheral blood are decreased and that the CD4/CD8 ratio is increased in patients with autoimmune diseases, including multiple sclerosis (MS) [16–21], rheumatoid arthritis (RA) [22, 23], SLE [24, 25], Sjögren's syndrome [25, 26], ...

What is the CD4:CD8 ratio for sarcoidosis? ›

High lymphocytosis and CD4/CD8 ratio in bronchoalveolar lavage fluid (BALF) are the main features of sarcoidosis (20). In patients with a clinical picture typical for sarcoidosis, an elevated CD4/CD8 ratio in BAL fluid may confirm the diagnosis and obviate the need for biopsy (21, 22).

What is a dangerously low CD4 count? ›

Normal CD4 count for healthy adults and teens: 500 to 1,200 cells per cubic millimeter. Low CD4 count: Below 500 cells per cubic millimeter. If you have HIV, a low CD4 count means that HIV has weakened your immune system. A CD4 count of 200 or fewer cells per cubic millimeter means that you have AIDS.

What is the reversed CD4 to CD8 ratio? ›

"A low or inverted CD4/CD8 ratio is an immune risk phenotype and is associated with altered immune function, immune senescence, and chronic inflammation in both HIV-infected and uninfected populations [8–11]. The prevalence of an inverted CD4/CD8 ratio increases with age.

What is the CD4:CD8 ratio in car T? ›

A CAR+CD4+ /CD8+ ratio higher than the cut point of 1.12 was associated with an increased risk of treatment failure at M3 (OR 23.3, p = 0.012) and M6 (OR 10, p = 0.028). The median 6-month PFS was 76% for patients with a ratio lower than 1.12% vs. 31% for the others.

What is a perfect CD4 count? ›

The CD4 count normal range is 500 to 1500 cell/mm^3. If a patient is left untreated, levels can drop below 200 cells/mm^3, which is one indication for the diagnosis of AIDS.

How to increase CD8 T cells naturally? ›

How can I boost my T-cells?
  1. Eat a well-balanced diet.
  2. Stay up-to-date on all vaccines.
  3. Avoid alcohol, or drink it in moderation.
  4. Don't smoke or vape and quit if you do.
  5. Sleep at least seven to eight hours each night.
  6. Engage in moderate exercise for at least 150 minutes a week.

What is the CD4:CD8 ratio in Hodgkin's lymphoma? ›

The CD4:CD8 ratio ranged from 2.1 to 8 (average 3.7). Lymph nodes in Hodgkin lymphoma cases (classical type; 10 cases) showed increased numbers of T cells (average 74%; range 51%–87%) with an increased CD4:CD8 ratio (average 11.2; range 3.9–28) and no aberrant pan-T antigen expression.

What CD4 count is considered immunocompromised? ›

For example, if your CD4 cell count is 200 or below, you are at risk of developing some serious illnesses and infections. Your doctor should recommend that you start HIV treatment urgently, without delay.

What autoimmune diseases are mediated by CD8? ›

In addition to the protective function of CD8+ T cells in viral infections and tumors, evidence primarily from studies in the experimental autoimmune encephalomyelitis (EAE), multiple sclerosis (MS), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), rheumatoid arthritis (RA), and vitiigo have been manifested ...

What is a bad CD4:CD8 ratio? ›

A normal CD4/CD8 ratio is greater than 1.0, with CD4 lymphocytes ranging from 500 to 1200/mm 3 and CD8 lymphocytes ranging from 150 to 1000/mm 3. If your ratio is higher than 1, it means your immune system is strong and you may not have HIV. If your ratio is less than 1, you may have: HIV.

What is the CD4:CD8 ratio for the elderly? ›

The prevalence of the inverted CD4:CD8 ratio is around 8% in adults (20–59 years old) and increases to 16% in people aged 60–94 years old [2]. Adults with inverted CD4:CD8 ratio show several remodeling enumerative and functional immune changes resembling premature senescence.

What is the ratio of CD4 to CD8 in EBV patients? ›

All Grade II cases showed EBV expression, whereas only 13 (39%) cases of Grade I disease were positive (P = 0.03). EBV-positive cases had a median CD4 to CD8 ratio of 1.62, whereas EBV-negative cases had a ratio of 3.86 (P = 0.01).

What does an elevated CD4 CD8 lymphocyte ratio indicate? ›

A normal CD4/CD8 ratio is greater than 1.0, with CD4 lymphocytes ranging from 500 to 1200/mm 3 and CD8 lymphocytes ranging from 150 to 1000/mm 3. If your ratio is higher than 1, it means your immune system is strong and you may not have HIV. If your ratio is less than 1, you may have: HIV.

What is important about CD4 and CD8 molecules? ›

Main Function of Both CD4 and CD8 Is to Enhance Lck Recruitment, Not Stabilize TCR–pMHC Interactions. Although CD4 does not stabilize TCR–pMHC interactions (9, 13, 14), like CD8, it does enhance T-cell responses (1, 9).

Why is CD4 percentage important? ›

For a physician, the CD4 cell count has become the best indicator of disease progression and is used to stage disease and guide medical therapy. Per the Center for Disease Control and Prevention (CDC), one of the indications for the diagnosis of AIDS is when CD4 cell count drops below 200 cells/mm^3.

What role do CD4 and CD8 proteins play in the immune response? ›

CD4+ T cells help antiviral CD8+ T cells in two main ways: they maximize CD8+ T cell population expansion during a primary immune response and also facilitate the generation of virus-specific memory CD8+ T cell populations. In addition to their helper functions, CD4+ T cells contribute directly to viral clearance.

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