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

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Human peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin (PHA) produce a factor that enhances neutrophil leukotriene B4 (LTB4) production.
• Leukotriene release enhancing factor (LREF) was purified from PBMC cultures.
• T lymphocytes, specifically CD4+ T cells, were identified as the primary source of LREF.

Purpose of the Study:

• To identify and characterize the factor produced by T lymphocytes that enhances neutrophil LTB4 production.
• To investigate the role of LREF in immune responses and inflammation.
• To explore the link between T cell-derived factors, neutrophils, and allergic diseases.

Main Methods:

• Purification of LREF using gel filtration and chromatofocusing.
• SDS-PAGE and isoelectric focusing to determine the molecular weight and isoelectric point of LREF.
• Stimulation of a human CD4+ T cell line with specific antigen (house dust mite) and accessory cells.
• Assay of LREF's effects on neutrophil adherence, cytotoxicity, and complement receptor expression.

Main Results:

• LREF was purified to a single band on SDS-PAGE with a molecular weight of 60 kDa and an isoelectric point of 5.0-5.2.
• Stimulated human CD4+ T cells generated leukotriene release enhancing activity (LREA).
• LREA enhanced neutrophil adherence, cytotoxicity against Schistosoma mansoni, and upregulated complement receptors CR1 and CR3, with minimal chemotactic activity.

Conclusions:

• Human T lymphocytes are a significant source of LREF, a factor that modulates neutrophil function.
• LREF acts as a mediator of inflammation, linking lipid mediators, neutrophils, and cell-mediated immunity.
• LREF plays a potential role in the pathogenesis of allergic diseases.