CD4+/CD8+ ratio

The CD4+/CD8+ ratio is the ratio of T helper cells (with the surface marker CD4) to cytotoxic T cells (with the surface marker CD8).

The CD4+/CD8+ ratio in the peripheral blood of healthy adults and mice is about 2:1, and an altered ratio can indicate diseases relating to immunodeficiency or autoimmunity.[1] An inverted CD4+/CD8+ ratio (namely, less than 1/1) indicates an impaired immune system.[2][3][4]

Both effector helper T cells (Th1 and Th2) and regulatory T cells (Treg) cells have a CD4 surface marker, such that although total CD4+ T cells decrease with age, the relative percent of CD4+ T cells increases.[5] The increase in Treg with age results in suppressed immune response to infection, vaccination, and cancer, without suppressing the chronic inflammation associated with aging.[5]

Decreased ratio

A reduced CD4+/CD8+ ratio is associated with reduced resistance to infection.[6]

A declining CD4+/CD8+ ratio is associated with ageing, and is an indicator of immunosenescence.[4][7] Compared to CD4+ T-cells, CD8+ T-cells show a greater increase in adipose tissue in obesity and aging, thereby reducing the CD4+/CD8+ ratio.[7]

Immunological aging is characterized by low proportions of naive CD8+ cells and high numbers of memory CD8+ cells, [4][8] particularly when cytomegalovirus is present.[4] Exercise can reduce or reverse this effect, when not done at extreme intensity and duration.[4]

HIV infection leads to low levels of CD4+ T cells (lowering the CD4+/CD8+ ratio) through a number of mechanisms, including killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that productively infected cells.[9] When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.[2][3] [4]

Patients with tuberculosis show a reduced CD4+/CD8+ ratio.[6]

See also

References
  1. Owen, Judith; Punt, Jenni; Stranford, Sharon (2013). Kuby Immunology. New York: W. H. Freeman and Company. p. 40.
  2. McBride JA, Striker R (2017). "Imbalance in the game of T cells: What can the CD4/CD8 T-cell ratio tell us about HIV and health?". PLOS Pathogens. 13 (11): e1006624. doi:10.1371/journal.ppat.1006624. PMC 5667733. PMID 29095912.
  3. Aiello A, Farzaneh F, Candore G, Caruso C, Davinelli S, Gambino CM, Ligotti ME, Zareian N, Accardi G (2019). "Immunosenescence and Its Hallmarks: How to Oppose Aging Strategically? A Review of Potential Options for Therapeutic Intervention". Frontiers in Immunology. 10: 2247. doi:10.3389/fimmu.2019.02247. PMC 6773825. PMID 31608061.
  4. Turner JE (2016). "Is immunosenescence influenced by our lifetime "dose" of exercise?". Biogerontology. 17 (3): 581–602. doi:10.1007/s10522-016-9642-z. PMC 4889625. PMID 27023222.
  5. Jagger A, Shimojima Y, Goronzy JJ, Weyand CM (2014). "Regulatory T cells and the immune aging process: a mini-review". GERONTOLOGY. 60 (2): 130–137. doi:10.1159/000355303. PMC 4878402. PMID 24296590.
  6. Yin Y, Qin J, Dai Y, Zeng F, Pei H, Wang J (2015). "The CD4+/CD8+ Ratio in Pulmonary Tuberculosis: Systematic and Meta-Analysis Article". Iranian Journal of Public Health. 44 (2): 185–193. PMC 4401876. PMID 25905052.
  7. Kalathookunnel Antony A, Lian Z, Wu H (2018). "T Cells in Adipose Tissue in Aging". Frontiers in Immunology. 9: 2945. doi:10.3389/fimmu.2018.02945. PMC 6299975. PMID 30619305.
  8. Tibbs TN, Lopez LR, Arthur JC (2019). "The influence of the microbiota on immune development, chronic inflammation, and cancer in the context of aging". MICROBIAL CELL. 6 (8): 324–334. doi:10.15698/mic2019.08.685. PMC 6685047. PMID 31403049.
  9. Kumar, Vinay (2012). Robbins Basic Pathology (9th ed.). p. 147. ISBN 9781455737871.


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