Humoral and cellular studies of eosinophils in reactive and myeloproliferative syndromes with marked eosinophilia.

In five patients with eosinophilia and myeloproliferative disorders, the IgE levels were normal, and immune complexes were not detected. In contrast, in six patients with reactive eosinophilia accompanying immunologic diseases, the IgE levels were elevated in five, and immune complexes were elevated in two. Five of six patients within the reactive group had positive rheumatoid factor titers by latex agglutination, while only one of five in the myeloproliferative group showed this finding. Purified eosinophils from patients with myeloproliferative diseases showed enhanced oxygen consumption responses during the ingestion of latex beads, relative to reactive eosinophils. The stimulated oxidative response of reactive eosinophils during phagocytosis of bacteria opsonized with antibody and complement was reduced, relative to myeloproliferative eosinophils. In vitro incubation of eosinophils with immune complexes reduced, by more than two-thirds, the increased oxidative responses of myeloproliferative eosinophils. Our findings suggest that eosinophilia seen in myeloproliferative diseases is an intrinsic part of the myeloproliferative process, which is not mediated or enhanced by allergic or immunologic reactions. The measurements reported here have potential value for differentiating reactive eosinophilic states from the eosinophilia accompanying myeloproliferative diseases.