Activation of oxidative burst and degranulation of porcine neutrophils by a homologous spleen galectin-1 compared to N-formyl-l-methionyl-l-leucyl-l-phenylalanine and phorbol 12-myristate 13-acetate

Galectins are a family of animal lectins defined by their β-galactoside-binding activities and a consensus sequence in their carbohydrate-recognizing domain (CRD). Relevant roles of galectins are described in adaptive immune response, innate immunity and modulation of the acute inflammatory response. We have extended our previous studies on a porcine spleen galectin-1 in relation to its functional roles such as polymorphonuclear neutrophils (PMNs) stimulation compared to well known PMN activators e.g. N-formyl-l-methionyl-l leucyl-l-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA). Relative to activation of NADPH-oxidase fMLP and PMA are stronger than galectin-1 plus cytochalasin B (CB) when the lectin is employed at low concentrations (gal-1 1 μM, 3.6+0.8 nm O2−/min/107 PMN). Higher doses of galectin-1 (10 μM) plus CB produced a significant activation of NADPH-oxidase (27.9+14.8 nm O2−/min/107 PMN) and stimulated PMN degranulation up to 50%. We propose that local galectin-1 concentrations under physiological conditions might reach suitable levels for pig PMN stimulation, and might be a natural inducer of O2− formation or degranulation. Porcine galectins might produce enhanced responses in vivo when they stimulate neutrophils in combination with some other stimuli.