GALECTIN-3 DOWN-REGULATES IL-5 GENE-EXPRESSION ON DIFFERENT CELL-TYPES

Galectin-3 is an animal lectin, formerly named E-binding protein or Ma c-2, which has been described to play an important role in some inflam matory processes by the implication of different cells and the increas e in cell adhesion functions through laminin binding activity. In this work we analyzed the role of galectin-3 in the modulation of Th2 cyto kines that have an important role in the development of the inflammato ry response. We have found that the addition of galectin-3 to human eo sinophils, the eosinophilic cell line EoL-3, PBMC, and an Ag-specific T cell line (CD4+) produced a selective inhibition of IL-5 transcripti on. No inhibitory effect was found on the IL-4 mRNA transcription rate . The inhibitory effect on IL-5 transcription was reversed by incubati on with lactose and using specific Ab against galectin-3. Galectin-3 i s able to induce inhibition of the IL-5 released in the supernatants f rom PBMC stimulated with phorbol 12,13-dibutyrate and anti-CD3, Simila r results were obtained when a T-specific cell line was stimulated wit h Ag, Also, EoL-3 stimulated with anti-CD32 produced IL-5 protein, the synthesis of which was partially inhibited by galectin-3. The present results demonstrate that galectin-3 induces a selective down-regulati on of IL-5 expression in different cell types, opening important new p ossibilities in the regulation of the allergic reactions.