We investigated whether non-pathogenic Saccharomyces cerevisiae and human commensal opportunistic pathogenic Candida albicans stimulate cytokine responses of human neutrophil-like HL-60 cells pre-treated with either 1 microM retinoic acid or 1.25% dimethyl sulfoxide (DMSO). Intact and heat-killed S. cerevisiae enhanced secretion of interleukin (IL)-1beta, IL-6, IL-8, IL-12, IL-18, MCP-1/CCL2 and TNF-alpha from retinoic acid-treated HL-60 cells, accompanied by alterations in mRNA expression of the cytokines. Heat-killed C. albicans promoted secretion of IL-6, IL-8, IL-12, MCP-1 and TNF-alpha, while intact C. albicans slightly enhanced secretion of IL-1beta, IL-8 and IL-18. In response to yeast stimuli, retinoic acid-treated HL-60 cells generally secreted cytokines more strongly than DMSO-treated HL-60 cells. Gene expression levels of Toll-like receptor (TLR)1, TLR2, TLR4, TLR6 and dectin-1 in HL-60 cells were additionally affected by retinoic acid or DMSO and by co-culturing with S. cerevisiae or C. albicans. Our results suggest that both intact and heat-killed S. cerevisiae and C. albicans induce cytokine responses of neutrophils in the intestine, and stimulate host immune function.