LAUSR

Objective Little has been reported regarding the reliability of methods for the purification of human blood eosinophils. We retrospectively reviewed our experience with 350 consecutive eosinophil isolations. Results Between January 2014 and December 2018, we conducted 350 eosinophil purifications from 83 donors. Absolute eosinophil count (AEC), calculated from hospital complete blood counts when available (n = 289), ranged from 32 to 1352 eosinophils/µL ( $$\bar{x} \pm {\text{SD}}$$ x ¯ ± SD : 179 ± 136/µL). Eosinophil yields ranged from 0.4 to 24.4 million cells per 20 mL of blood drawn ( $$\bar{x} \pm {\text{SD}}$$ x ¯ ± SD : 3.1 ± 1.9 million eosinophils) with > 98% purity. Comparing AEC to actual yield, recovery was 87% ± 29% ( $$\bar{x} \pm {\text{SD}}$$ x ¯ ± SD ) and AEC strongly correlated with yield. To explore the reproducibility of yield, a subsequent analysis was limited to those donors drawn ≥ 3 times (N = 35), and there was no difference in the average coefficient of variation for yield between allergic and non-allergic donors. Viability of isolated eosinophils was consistently > 95% and after 24 h of culture did not differ between allergic and non-allergic donors. We conclude that this immunomagnetic separation method for human eosinophil isolation from whole blood is a reliable, reproducible technique for obtaining an average of 87% yield with high purity and viability.