SECA, a new mediator of the human eosinophil response

Eosinophil response in guinea pig skin to a low molecular weight eosinophil chemotactic factor extracted from livers of mice with schistosomiasis

A low-molecular weight eosinophil chemotactic factor (ECF-G), isolated and partially purified from livers of mice with schistosomiasis, was injected intradermally into guinea pigs. Biopsies obtained were studied for inflammatory cell accumulation in the injected sites and compared with those in the control sites injected with phosphate buffered saline. Tissue eosinophilia was seen as early as 1 hr after injection of ECF-G, but not in the control site. The increase of eosinophilia appeared biphasic with peaks at 6 and 24 hr. Mast cells increased in both ECF-G and saline injected sites and the increase was still found at 120 hr after injection. Neutrophils also increased in both ECF-G and saline injected sites but disappeared within 48 hr. These findings indicate that ECF-G is a tissue and species nonspecific eosinophil chemotactic factor, and injection of ECF-G initiates interaction of eosinophils and mast cells in the skin.

Malignant lymphoma associated with marked eosinophilia

A 60-year-old black man with poorly differentiated lymphocytic lymphoma presented with generalized lymphadenopathy and marked eosinophilia. Extensive evaluation of the eosinophils revealed them to be normal morphologically and functionally. The patient responded to corticosteroid therapy with resolution of the lymphadenopathy and reversion of the peripheral blood counts to normal limits. Recurrence of the original clinical picture within months prompted institution of systemic chemotherapy. Response was transient, and the patient expired after an unremitting downhill course. Recent advances in our knowledge of mechanisms of eosinophilia and eosinophil function are reviewed. The relationship of lymphoma to eosinophilia is discussed.

Partial characterization of in vivo chemotactic activity: comparison to human C5a

Spontaneous eosinophil chemotactic activity (SECA) can mediate the directed movement of human eosinophils and neutrophils. Preliminary characterization of SECA has been carried out. SECA is nondialyzable and heat-stable (56 degrees C, 30 min). Chromatography on Sephadex G-75 demonstrated that SECA had elutional and functional properties similar to C5a (prepared from endotoxin-activated normal sera). Polyacrylamide gel electrophoresis (PAGE) with the use of 15% bisacrylamide gels of lyophilized, chemotactically active column fractions demonstrated a single protein band of identical electrophoretic mobility from either SECA or C5a preparations. Enzymatic hydrolysis with carboxypeptidase B, a known inhibitor of C5a activity, significantly decreased chemotactic activities of C5a and SECA. The addition of purified anti-C5 to either SECA or C5a significantly inhibited chemotactic activity. SECA is naturally occurring chemotactic activity identical to human C5a. Thus C5a may be an important source of in vivo chemotactic activity in various inflammatory disorders.