IL-6-inducing whole yeast-based immunotherapy directly controls IL-12-dependent CD8 T-cell responses

J Immunother. 2012 Jan;35(1):14-22. doi: 10.1097/CJI.0b013e3182356888.

Abstract

In current clinical trails, whole yeast-based immunotherapy expressing hepatitis C viral antigens demonstrated statistically significant improvement in end of treatment responses when combined with type I interferon based standard of care, even in standard of care resistant patients. Although preclinical data suggest yeast vaccination, such as type I interferon, facilitates CD8 T-cell immunity, the capacity of yeast to generate immunity in patients resistant to type I interferon calls into question the mechanism(s) underpinning the efficacy of this approach. We show yeast and a Toll-like receptor exclusive agonist, Pam3Cys, differ in CD8 T-cell generation when combined with an agonistic CD40 antibody. Although both yeast and PamCys were largely Toll-like receptor dependent, the primary CD8 response generated by yeast was significantly less than Pam3Cys in wild-type hosts even in a CD4 T-cell-deficient setting. In addition, immunization of IL6 mice with yeast produced a 3-fold to 6-fold increased CD8 response while the Pam3Cys response was unaffected. The yeast but not Pam3Cys-driven CD8 response was inhibited in both wild-type and IL-6 hosts by blocking interleukin (IL)-12. In addition, IL6 mice had increased CD86 expression on their dendritic cells after yeast immunization also inhibited by IL-12 blockade. Collectively, our results indicate the CD8 T-cell response to yeast but not Pam3Cys is influenced by IL-6-mediated control of IL-12 critical for dendritic cell activation. To our knowledge this is the first demonstration that yeast directly influence IL-12-associated CD8 T-cell immunity providing an additional route whereby recombinant yeast may provide efficacy independent of type I interferon.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD40 Antigens / immunology
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism*
  • CD8-Positive T-Lymphocytes / pathology
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Differentiation / immunology
  • Cells, Cultured
  • Cysteine / administration & dosage
  • Cysteine / analogs & derivatives
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism*
  • Dendritic Cells / pathology
  • Immunotherapy / methods*
  • Interferon Type I / immunology
  • Interleukin-12 / genetics
  • Interleukin-12 / immunology
  • Interleukin-12 / metabolism
  • Interleukin-6 / genetics
  • Interleukin-6 / immunology
  • Interleukin-6 / metabolism*
  • Lipoproteins / administration & dosage
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / genetics
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Saccharomyces cerevisiae / immunology*
  • Th17 Cells / immunology
  • Vaccination

Substances

  • CD40 Antigens
  • Interferon Type I
  • Interleukin-6
  • Lipoproteins
  • Interleukin-12
  • 2,3-bis(palmitoyloxy)-2-propyl-1-palmitoylcysteine
  • Cysteine