Basal or dectin-1-activated LTB4/BLT1 signaling elicits Gαi activation that results in enhanced expression of GM-CSF. This cytokine potentiates expression of PU.1, which carries out transcription of dectin-1, augmenting dectin-1 protein expression and responsiveness, as evidenced by binding, phagocytosis, cytokine secretion, and neutrophil recruitment in response to challenge with C. albicans, zymosan, or the fungal glucan curdlan. LTB4 generation in response to dectin-1 ligation represents an autocrine self-amplifying loop.