, 1999). Imiquimod at 0.5 μg mL−1 was optimal for human PBMC production of TNF-α, IFN-γ, IL-1, IL-6, IL-8, IL-10, IL-12, GM-CSF, G-CSF, and MIP-1α, with a 24-h incubation (Stanley, 2002). Although we see more did not define in the present

study as to which cells in murine PBMC elaborate the cytokines we identified, other studies, with imiquimod, have indicated that the cells in human PBMC producing proinflammatory cytokines are monocyte/macrophages and B cells (Megyeri et al., 1995). Analysis of cellular requirements in human PBMC for cytokine production induced by imiquimod indicated that T-lymphocytes were responsible for IFN-γ production, but required IL-12 and IFN-γ from imiquimod-stimulated macrophages (Wagner et al., 1999). Other studies with TLR-7 agonists suggest that monocytes are the main cells found in abundance in human peripheral blood that are responsive. This was also true of the stronger response induced by TLR-8 and TLR-7/8 agonists, as would be relevant to 3M-003 (Gorden et al., 2005). Although responses of mouse spleen CAL-101 supplier cells to imiquimod

have been reported (Wagner et al., 1999), we are not aware of studies using mouse PBMC and imiquimod. Here, we report novel findings that 3M-003-stimulated mouse PBMC produce high levels of TNF-α and IL-12, but little to no IFN-γ in the time frame examined. Supernatants from mouse PBMC cultures containing high levels of TNF-α and IL-12 were sufficient to induce enhanced candidacidal activity in macrophages, neutrophils, and monocytes. That macrophages are upregulated by PBMC-produced factors in supernatants was evidenced by the 3M-003 carryover in supernatants being much less than the concentrations we show required for consistent direct macrophage activation. Supernatant neutralization and/or addition (e.g. TNF-α, IL-12, or TNF-α+IL-12) experiments are warranted to further elucidate the phagocyte activation mechanism induced by supernatants. These compounds are potentially useful for antifungal therapy.

This could especially be important in the common entity, neonatal candidiasis (Chapman & Faix, 2003), because TLR-8 agonists appear to be particularly potent activators of the neonatal immune system (Philbin & Levy, 2007). It would be of interest to ascertain whether the antifungal activity would extend to hyphal forms and to other fungi. Systemic use of these BCKDHA compounds is under study as an antineoplastic (Dudek et al., 2007; Harrison et al., 2007; Smith et al., 2007). Cytokine induction has been noted after oral administration (Dahl, 2002; Harandi et al., 2003). An additional possible mechanism of action of the imidazoquinolines is TLR-independent immunomodulation by antagonism of adenosine receptors (Philbin & Levy, 2007). Agonists of human TLR-8 can also reverse the function of regulatory T cells; caution may need to be exercised for possible overabundance of an inflammatory response with such agents (Philbin & Levy, 2007).