AC-1

AC-1 is an extracellular polysaccharide produced by *Acetobacter polysaccharogenes*, primarily composed of (1,4)-beta-D-glucan with branches of glucosyl residues. It functions as an immunomodulator, enhancing antitumor activities by inducing the production of interleukin (IL)-12 p40 and tumor necrosis factor-alpha (TNF-alpha) by macrophage cell lines through Toll-like receptor-4 (TLR4) signaling. Preclinical studies in murine B16 melanoma models (MHC class I-negative B16L and MHC class I gene-transfected B16K(b) cells) have shown that AC-1 retards tumor growth. Its antitumor mechanism involves augmenting natural killer (NK) cell activity and cytotoxic T-lymphocyte responses, suggesting potential prophylactic application for human neoplasms irrespective of MHC class I expression levels.