DENSITY HETEROGENEITY OF EOSINOPHIL LEUKOCYTES - INDUCTION OF HYPODENSE EOSINOPHILS BY PLATELET-ACTIVATING FACTOR

  • 1 September 1989
    • journal article
    • research article
    • Vol. 68  (1) , 140-143
Abstract
We have examined the induction of hypodense eosinophila by platelet-activating factor (PAF), a mediator which may be involved in eosinophil activatoin in allergic diseases. Guinea-pig eosinophils were incubated with buffer or PAF and applied to continuous Percoll density gradients. Cellular density ranged from 1.0142 to 1.1369 g/ml. Peak eosinophil density in control was 1.0887 .+-. 0.0008 g/ml (mean .+-. SEM), and 91.1 .+-. 1.4% of eosinophils were distributed between 1.0810 and 1.1000 g/ml. Preincubation of eosinophils with PAF(10-7 M) resulted in a time-dependent and non-cytolytic increase of the number of hypodense eosinophils, with peak densities after incubation for 1 hr and 2 hr of 1.-834 .+-. 0.0014 (n = 4, P < 0.05) and 1.0755 .+-. 0.007 g/ml (n = 6, P < 0.01), respectively. After incubation for 2 hr, 82.0 .+-. 4.9% (n = 6) eosinophils showed a density lower than 1.080 g/ml. Lyso-PAF, the inactive precursor and metabolite of PAF, at a concentration of 10-7 M had no effect on cell density. The specific PAF receptor antagonist WEB 2086 (10-6 M) inhibited the PAF-induced density shift by 87.0 .+-. 5.3%. Our results demonstrate that a single mediator is able to induce the formation of hypodense eosinophils. We conclude that the appearance of hypodense eosinophils in allergic diseases such as asthma may occur, at least in part, in response to inflammatory mediator which activate these cells.

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