Rapid clonal expansion and prolonged maintenance of memory CD8+ T cells of the effector (CD44highCD62Llow) and central (CD44highCD62Lhigh) phenotype by an archaeosome adjuvant independent of TLR2

J Immunol. 2007 Feb 15;178(4):2396-406. doi: 10.4049/jimmunol.178.4.2396.

Abstract

Vaccines capable of eliciting long-term T cell immunity are required for combating many diseases. Live vectors can be unsafe whereas subunit vaccines often lack potency. We previously reported induction of CD8(+) T cells to Ag entrapped in archaeal glycerolipid vesicles (archaeosomes). In this study, we evaluated the priming, phenotype, and functionality of the CD8(+) T cells induced after immunization of mice with OVA-Methanobrevibacter smithii archaeosomes (MS-OVA). A single injection of MS-OVA evoked a profound primary response but the numbers of H-2K(b)OVA(257-264)-specific CD8(+) T cells declined by 14-21 days, and <1% of primarily central phenotype (CD44(high)CD62L(high)) cells persisted. A booster injection of MS-OVA at 3-11 wk promoted massive clonal expansion and a peak effector response of approximately 20% splenic/blood OVA(257-264)-specific CD8(+) T cells. Furthermore, contraction was protracted and the memory pool (IL-7Ralpha(high)) of approximately 5% included effector (CD44(high)CD62L(low)) and central (CD44(high)CD62L(high)) phenotype cells. Recall response was observed even at >300 days. CFSE-labeled naive OT-1 (OVA(257-264) TCR transgenic) cells transferred into MS-OVA-immunized recipients cycled profoundly (>90%) within the first week of immunization indicating potent Ag presentation. Moreover, approximately 25% cycling of Ag-specific cells was seen for >50 days, suggesting an Ag depot. In vivo, CD8(+) T cells evoked by MS-OVA killed >80% of specific targets, even at day 180. MS-OVA induced responses similar in magnitude to Listeria monocytogenes-OVA, a potent live vector. Furthermore, protective CD8(+) T cells were induced in TLR2-deficient mice, suggesting nonengagement of TLR2 by archaeal lipids. Thus, an archaeosome adjuvant vaccine represents an alternative to live vectors for inducing CD8(+) T cell memory.

Publication types

  • Comparative Study

MeSH terms

  • Adjuvants, Immunologic* / pharmacology
  • Animals
  • Antigen Presentation / immunology
  • CD8-Positive T-Lymphocytes / immunology*
  • Female
  • Hyaluronan Receptors / immunology*
  • Immunologic Memory*
  • L-Selectin / immunology*
  • Listeria monocytogenes / immunology
  • Methanobrevibacter / immunology*
  • Mice
  • Mice, Knockout
  • Ovalbumin / immunology
  • Receptors, Interleukin-7 / immunology
  • Time Factors
  • Toll-Like Receptor 2 / deficiency
  • Toll-Like Receptor 2 / immunology*

Substances

  • Adjuvants, Immunologic
  • Cd44 protein, mouse
  • Hyaluronan Receptors
  • Receptors, Interleukin-7
  • Toll-Like Receptor 2
  • L-Selectin
  • Ovalbumin