Biomarkers of Immunity: Bands

Optimal Takeaways

Bands are immature neutrophils, also known as immature granulocytes that increase with acute bacterial infection and sepsis. The likelihood of sepsis increases as band levels increase in the blood. Cytokines stimulate the release of bands into circulation and may be observed with surgery, bleeding, tissue damage, and certain cancers. Low levels of bands are observed in a healthy homeostatic state and may not appear in circulation at all.

Standard Range: 0.00 – 5.00%

The ODX Range: 0.00 – 3.00%           

Low band counts are associated with the absence of infection.

High band counts are associated with bacterial infection, trauma (Pagana 2021), and sepsis (Mare 2015, Hsueh 2021).

Overview

Band cells, also called stab cells, are a type of immature neutrophil. Bands may be released into circulation early on during significant stimulation of neutrophil production, which can occur with trauma or acute bacterial infection. This phenomenon is called a “shift to the left” and often characterizes a persistent acute bacterial infection (Pagana 2021).

Elevated band cell levels are associated with sepsis. They may help differentiate sepsis from non-infectious systemic inflammatory response syndrome (SIRS), a condition caused by trauma, stress, and cardiopulmonary bypass. A cut-off of 8.5% bands or above suggests definite sepsis. Band cells represent the last step of maturation before developing into segmented neutrophils and may be able to perform some of the functions of mature neutrophils. Precursors to band cells, i.e., myelocytes and metamyelocytes, are not significantly functional and may indicate patient deterioration and impending organ dysfunction (Mare 2015). Prospective observational research on a cohort of ICU patients found that band cells expressed an inflammatory phenotype and were capable of innate immune functions, including free radical production and the killing and phagocytizing of bacteria (Drifte 2013).

One retrospective cohort study of 22,820 patients found that the likelihood of bloodstream infection increased significantly as bands increased to 1-2%, with progressively increased likelihood as bands increased further to 3-4%, 5-10%, and finally greater than 10%. Band levels greater than 10% were more likely to be associated with gram-negative bacilli infection, followed by S. aureus, Candida spp., beta-hemolytic streptococci, and S. pneumoniae. In-hospital mortality also increased as bands increased. Researchers recommend prospective studies to confirm these findings (Hsueh 2021).

Cytokines associated with infection stimulate the bone marrow to release more immature cells, including band cells, though this shift to the left may be delayed in septic shock. Other causes of increased circulating bands include hemorrhage, surgery, tissue necrosis, myeloproliferative disease, and exogenous granulocyte cell stimulating factor administration. Some research suggests that bands above 3% may indicate infection (Farkas 2020).

References

Drifte, Geneviève et al. “Innate immune functions of immature neutrophils in patients with sepsis and severe systemic inflammatory response syndrome.” Critical care medicine vol. 41,3 (2013): 820-32. doi:10.1097/CCM.0b013e318274647d

Farkas, Joshua David. “The complete blood count to diagnose septic shock.” Journal of thoracic disease vol. 12,Suppl 1 (2020): S16-S21. doi:10.21037/jtd.2019.12.63

Hsueh, Leon et al. “Elevated bands as a predictor of bloodstream infection and in-hospital mortality.” The American journal of emergency medicine vol. 41 (2021): 205-208. doi:10.1016/j.ajem.2020.11.049

Kipnis, Eric. “Neutrophils in sepsis: battle of the bands.” Critical care medicine vol. 41,3 (2013): 925-6. doi:10.1097/CCM.0b013e31828042d8

Mare, Tracey Anne et al. “The diagnostic and prognostic significance of monitoring blood levels of immature neutrophils in patients with systemic inflammation.” Critical care (London, England) vol. 19,1 57. 25 Feb. 2015, doi:10.1186/s13054-015-0778-z

Pagana, Kathleen Deska, et al. Mosby's Diagnostic and Laboratory Test Reference. 15th ed., Mosby, 2021.