Biomarkers of Immunity: Basophils

Optimal Takeaways

Basophils, a subset of white blood cells, are usually found in low levels in circulation, accounting for less than 1% of total WBCs under homeostatic circumstances. However, basophils increase, become activated, and release inflammatory compounds in association with parasitic infection, allergies, autoimmune disease, chronic inflammation, inflammatory bowel disease, uremia, and some malignant conditions such as leukemia. Basophil levels may be elevated in hypothyroidism and low in hyperthyroidism.

Basophils, Absolute

Standard Range: 0.00 – 0.20 k/cumm (0.00 – 0.20 giga/L)

The ODX Range: 0.00 – 0.10 k/cumm (0.00 – 0.10 giga/L)

Basophils %

Standard Range: 0.00 – 1.00%

The ODX Range: 0.00 – 1.00%

Low basophil counts are associated with hyperthyroidism (Deyrup 2022), basopenia, acute allergic reactions, and the stress response (Pagana 2021).

High basophil counts are associated with allergies, hypersensitivity reactions (Justiz Vaillant 2022, Siracusa 2013), basophilia, uremia, leukemia, myeloproliferative disease (e.g., myelofibrosis, polycythemia rubra vera) (Pagana 2021), hypothyroidism, chronic inflammation, autoimmune disorders (Deyrup 2022), parasitic infection, and the inflammatory bowel diseases Crohn’s and ulcerative colitis (Karasuyama 2018). Basophils also increase and respond to a variety of environmental stimuli, including pollen, venom, and drugs, and can accumulate in lupus nephritis, and skin and kidney allograph responses (Siracusa 2013).

Overview

Basophils usually make up less than 1% of total white blood cells. They have similar functions to mast cells in the process of inflammation and allergic response. The binding of IgE to basophils causes them to release inflammatory mediators, including histamine, platelet-activating factor, and phospholipase A, substances that then cause classic allergy symptoms. Heparin and sulfated glycosaminoglycans are also released (Tigner 2021).

Sensitized basophils also release leukotrienes and prostaglandins that promote systemic bronchoconstriction, vasodilation, and increased vascular endothelium permeability. In the latter phases of an immune hypersensitivity response, basophils may continue to be stimulated 8-12 hours after removal of the antigen (Justiz Vaillant 2022). Basophil activation tests have been developed to detect allergic reactions, and to evaluate basophil degranulation and whether it is characterized as “anaphylactic” or “piecemeal” degranulation (McGowan 2013). Blocking IgE has been found to reduce IgE-mediated stimulation of basophils and reduces their release of histamine and other inflammatory mediators. However, some allergic reactions associated with basophils are independent of IgE activity (Siracusa 2013).

Basophils take part in the promotion of allergic inflammation in the GI tract, respiratory system, and skin, and are present in the skin lesions observed with urticaria, atopic dermatitis, and Stevens-Johnson syndrome. Basophils participate in systemic anaphylaxis as well. Basophils also promote the non-allergic inflammation seen in autoimmune disorders and inflammatory bowel disease. However, they also play a protective role in the immune response against parasitic infection (Karasuyama 2018).

Basophils are able to promote type 2 helper cell responses during parasite exposure but may also be able to restrict type 2 inflammation and preserve tissue from parasite-associated injury. Research also indicates that basophils participate in neuro-immune crosstalk (Peng 2021).

Signaling from commensal microbes appears to beneficially influence and regulate basophil development. Researchers speculate that the association between allergic inflammation and antibiotic exposure during childhood may be due to loss of commensal signaling, which can dysregulate basophils (Siracusa 2013).

References

Deyrup, Andrea T et al. “Essential laboratory tests for medical education.” Academic pathology vol. 9,1 100046. 13 Sep. 2022, doi:10.1016/j.acpath.2022.100046

Justiz Vaillant, Angel A., et al. “Physiology, Immune Response.” StatPearls, StatPearls Publishing, 26 September 2022.

Karasuyama, Hajime et al. “Multifaceted roles of basophils in health and disease.” The Journal of allergy and clinical immunology vol. 142,2 (2018): 370-380. doi:10.1016/j.jaci.2017.10.042

McGowan, Emily C, and Sarbjit Saini. “Update on the performance and application of basophil activation tests.” Current allergy and asthma reports vol. 13,1 (2013): 101-9. doi:10.1007/s11882-012-0324-x

Peng, Jianya, and Mark C Siracusa. “Basophils in antihelminth immunity.” Seminars in immunology vol. 53 (2021): 101529. doi:10.1016/j.smim.2021.101529

Siracusa, Mark C et al. “Basophils and allergic inflammation.” The Journal of allergy and clinical immunology vol. 132,4 (2013): 789-801; quiz 788. doi:10.1016/j.jaci.2013.07.046

Tigner, Alyssa, et al. “Histology, White Blood Cell.” StatPearls, StatPearls Publishing, 19 November 2021.