Functional heterogeneity of human eosinophil chemotactic lymphokines

We have previously isolated two OKT4-positive T lymphocyte-derived eosinophil chemotactic factors (LDECF) with MW of about 45-60 kDa of which production is different in antigen or mitogen dependency (1-4). The production of a LDECF from patients with parasite disease (LDECF-PD) is dependent on antigen or mitogen stimulation, whereas another LDECF from patients with hypereosinophilic syndrome (HES) is independent. Further purification of these LDECF with isoelectric focusing reveals that an isoelectric point of LDECF-HES is about 6.0 and that of LDECF-PD is around 7.0 to 8.0. Little or no activity of partially purified LDECF-HES and LDECF-PD is suppressed by treatment with monoclonal antibodies against GM-CSM, IL-3, and IL-5, which activate eosinophils. LDECF-HES and LDECF-PD attract eosinophils from healthy individuals. In contrast, eosinophils from patients with HES are attracted by LDECF-HES but not LDECF-PD. LDECF-HES enhances the expression of Fc epsilon receptor II (Fc epsilon RII) and Fc gamma receptor III (Fc gamma RIII) but not that of CR1 on eosinophils, whereas LDECF-PD enhances their CR1 and Fc gamma RIII expression but not Fc epsilon RII expression. Moreover, treatment with LDECF-PD suppresses the release of eosinophilic cationic protein (ECP) from eosinophils, whereas that with LDECF-HES fails. Treatment of eosinophils with phorbol myristate acetate enhances ECP release from eosinophils but it fails to enhance the intracellular ECP level. However, the intracellular ECP level is elevated by stimulation with phorbol myristate acetate if eosinophils were previously treated with LDECF-HES but not with LDECF-PD. These results suggest that various kinds of LDECF are produced according to the nature of diseases, and that each LDECF has functional heterogeneity on eosinophils.