P70 Blood eosinophil counts in normal controls with no history of allergic disease

Abstract

BackgroundThe beneficial effect of corticosteroids and anti-interleukin (IL)-5 on exacerbations of airway disease becomes apparent at blood eosinophil counts above 0.15 × 109/L, well within the normal range. One potential explanation is that the upper limit of the normal range is artificially high because studies have included patients with allergic disease and eosinophilic inflammation. We have assessed the normal range for blood eosinophil counts in volunteers with no self-reported history of allergic disease and compared this with the findings from a more traditional control population.MethodsWe recruited 78 volunteers (15 male) with a mean age of 38.8 years. Volunteers with a self-reported history of asthma, allergic rhinitis and/or eczema were excluded. The differential cell count was carried out using sysmex XN analyser and serum IgE measured using automated enzyme immunoassay by Phadia Immunocap equipment. Result were compared with an unscreened population (n = 120) used to calculate our local normal ranges.ResultsOne outlier value of 0.79 × 109/L, (>5 SD above the mean) was excluded from further analysis. In the remainder the mean blood eosinophil count was 0.15 × 109/L with an upper limit of normal range of 0.27 × 109/L. Volunteers with no self-reported history of allergic disease but an IgE >120 iu/L and/or positive specific IgE to house dust mites or grass were not statistically different. The mean blood eosinophil count in the laboratory population was 0.19 × 109/L (p 0.018 vs our population) and the upper limit of normal range 0.42 × 109/L.ConclusionsThe upper limit of the normal range for blood eosinophil count is lower in a population who have no clinical history of allergic disease.

Eosinophils in COPD: just another biomarker?

“…Up to 40% of the general population have been found to have atopy 52 . In a small calibration study 47 , the circulating eosinophil count mean and upper limit of normal (95% upper limit) reference range for all healthy controls was found to be 190 (420) cells/μL. Repeated reference laboratory calibration, in a separate healthy control population, where atopic (self-reported or elevated IgE) controls were excluded, demonstrated that the mean (95% upper limit) circulating eosinophil count was 150 (270) cells/μL.…”

“…Peripheral blood eosinophil counts in asthma, chronic obstructive pulmonary disease and healthy controls. Data derived from Bafadhel et al 42 and Anand et al 47 For a biomarker to be relevant and valid, although not in the original biomarker definitions described above by the WHO 34 , its presence needs to be stable or repeatable over time. This is essential when considering life-long or expensive treatment options based upon the presence or level of the relevant biomarker i.e.…”

Year in review 2015: Asthma and chronic obstructive pulmonary disease

“…In retrospect, it makes sense that peripheral eosinophilia might reflect sputum eosinophilia, but this straightforward measure may have obscured by potentially clinically useful measurements being in the ‘normal’ range. It is worth noting that ‘normal’ ranges were calculated using both atopic and non‐atopic individuals; recalculating without atopic patients reduces the normal range to around the level reflective of sputum eosinophilia . The important clinical question is of course ‘is it useful’, rather than ‘is it normal?’ Can blood eosinophils help titrate therapy like sputum eosinophils?…”

“…It is worth noting that 'normal' ranges were calculated using both atopic and non-atopic individuals; recalculating without atopic patients reduces the normal range to around the level reflective of sputum eosinophilia. 31,32 The important clinical question is of course 'is it useful', rather than 'is it normal?' Can blood eosinophils help titrate therapy like sputum eosinophils?…”

Chronic rhinosinusitis: Eosinophil blood reference values and decision limits and tissue count intravariability

“… 2 Recently, the median eosinophil count in health was shown as 0.11 × 10 9 /l and 0.15 × 10 9 /l (with an upper limit of normal range at 0.27 × 10 9 /l). 34 In asthma, corticosteroid and anti‐IL‐5 anti‐eosinophil treatment response is seen in patients with eosinophils at 0.15 × 10 9 /l. 5 Blood levels of ≥250 cells/l (ie 0.25 × 10 9 /l) are the current set criteria for selection of CRS patients for biologics that target key T2 inflammatory signalling points.…”