Increased numbers of hypodense eosinophils in the blood of patients with bronchial asthma.

We investigated the density of blood eosinophils from patients with asthma using polyvinylpyrrolidone-coated silica gel (Percoll) discontinuous density gradient centrifugation of peripheral blood leukocytes. Ten patients with allergic asthma, 10 normal subjects, and 2 patients with the hypereosinophilic syndrome (HES) were studied. The density distribution profiles of eosinophils from normal subjects showed: (1) peaks at densities of 1.085 to 1.090 g/ml and (2) inflection points or nadirs near 1.082 g/ml, below which only 10% of eosinophils were found. On the basis of these results, we divided eosinophils into 2 subpopulations: normodense (greater than 1.082 g/ml) and hypodense (less than 1.082 g/ml). Densities of eosinophils from patients with asthma and HES peaked at 1.083 and 1.076 g/ml (mean values), respectively, significantly lighter than eosinophils from normal donors (p less than 0.005 and p less than 0.001, respectively). The proportions of hypodense eosinophils in patients with asthma and HES were 35 and 95%, respectively, and were significantly greater than that in normal donors (p less than 0.002 and p less than 0.001, respectively). The density distribution profiles of a normal subject were stable over time, but those of asthmatic patients varied with time. For the 22 participants, there was a positive correlation between log-transformed blood eosinophil counts and the percentage of hypodense eosinophils (r = +0.86, p less than 0.001). Similarly, for 15 of them, plasma eosinophil granule major basic protein correlated with the numbers of peripheral blood eosinophils (r = +0.92, p less than 0.0005) and hypodense eosinophils (r = +0.92, p less than 0.0005). Thus, a portion of the eosinophils in asthmatic patients and most of the eosinophils in patients with HES are hypodense.(ABSTRACT TRUNCATED AT 250 WORDS)