Langerhans cell deficiency impairs Ixodes scapularis suppression of Th1 responses in mice

Infect Immun. 2009 May;77(5):1881-7. doi: 10.1128/IAI.00030-09. Epub 2009 Mar 9.

Abstract

Ixodes scapularis ticks transmit a number of human pathogens, including the Lyme disease spirochete Borrelia burgdorferi. I. scapularis suppresses host immunity in the skin to promote feeding and systemically skew T-helper (Th)-cell differentiation toward Th2 cells in secondary lymphoid organs. Although components of tick saliva are known to influence Th-cell polarization, the mechanism whereby tick feeding in the skin modulates regional and systemic Th-cell responses is unknown. In this study, the role of the epidermal Langerhans cell (LC) subset of skin dendritic cells in tick-mediated Th1/Th2-cell immunomodulation was assessed. Mice deficient in LCs (Langerin-DTA mice) exhibited enhanced lymph node (LN) concanavalin A (ConA)-induced Th1 responses after tick infestation in comparison to results for uninfested Langerin-DTA or wild-type (WT) mice, whereas effects on Th2-cell production of interleukin 4 were more variable. Nonetheless, the altered T-cell response did not impact tick feeding or refeeding. Gamma interferon production by ConA-stimulated LN cells of both WT and LC-deficient mice was enhanced by as much as fourfold after B. burgdorferi-infected-tick feeding, indicating that immunomodulatory effects of tick saliva were not able to attenuate the Th1 immune responses induced by this pathogen. Taken together, these findings show a requirement for LCs in the tick-mediated attenuation of Th1 responses in regional lymph nodes but not in the spleens of mice and show that the presence of a pathogen can overcome the Th1-inhibitory effects of tick feeding on the host.

Publication types

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

MeSH terms

  • Animals
  • Feeding Behavior
  • Immune Tolerance*
  • Ixodes / immunology*
  • Langerhans Cells / immunology*
  • Lymph Nodes / immunology
  • Mice
  • Mice, Knockout
  • Saliva / immunology
  • Spleen / immunology
  • Th1 Cells / immunology*
  • Th2 Cells / immunology