Leukotriene release enhancing factor. Purification, specific allergen induction, and further biologic properties.

Human PBMC cultured with PHA produced a factor which enhanced neutrophil LTB4 production. After progressive purification by gel filtration and chromatofocusing, leukotriene release enhancing factor (LREF) gave a single band on SDS-PAGE corresponding to a Mr of 60 kDa and a isoelectric point of 5.0 to 5.2. Human T lymphocytes were identified as a source of LREF because a long term human CD4+ T cell line, specific for house dust mite (Dermatophagoides farinae) generated leukotriene release enhancing activity (LREA) when stimulated with the inducing Ag together with irradiated accessory cells. Cultures of accessory cell and Ag alone did not induce neutrophil activation. Similarly, control cultures using an irrelevant allergen (grass pollen) failed to produce this activity. Stimulation of PBMC with anti-CD3 mAb also generated LREA. LREA had other neutrophil-associated biologic activities. These included the enhancement of neutrophil adherence to nylon wool, increased cytotoxicity of opsonised schistosomula of Schistosoma mansoni and upregulation of C receptors (CR1 and CR3). LREA had minimal neutrophil chemotactic activity. Therefore, LREF has potential as a mediator of inflammation and provides a link between lipid mediators, neutrophils, and cell-mediated immunity in the context of allergic diseases.