MAINTENANCE OF MEMORY CD4 CELLS

THE ROLE OF TLR2 ENGAGEMENT

Abstract

Objective: Ligation of TLR by distinct pathogen components provides essential
signals for T cell priming, although how individual TLR engagement affects memory T cells
induction and maintenance in vivo is not well defined. The aim of the present study was to
investigate the role of TLR2 engagement in the maintenance of memory T cells. Method: Ova
specific KJ-1 cells from DO-11 mice were adoptively transferred to Balb/c mice. T cells were
activated with Ova in the host of adoptive cells to induce memory. To examine the function and
+ maintenance of memory cells in vivo, CD4 T cells were transferred to mice, which were then
challenged with Ova-BLP and looked for memory cell proliferation. Furthermore, the memory T
cells harvested from lymph node and spleen of Balb/c mice were treated with Ova and BLP in vitro
to establish the effects of TLR2 ligation on proliferation of memory T cells. Two different protocols
were used to confirm the same phenomenon. Results: Two different protocols show that
memory T cells proliferation in vivo and in vitro can be maintained by TLR2 agonist (BLP). We
demonstrate that antigen specific CD4 T cells undergo extensive proliferation in the presence of
Ova and TLR2 agonist, in fact with TLR2 priming results in greater expansion. Moreover, TLR2
agonist priming of ova-specific CD4 T cells resulted in a higher frequency of persisting ova/BLP
specific memory CD4 T cells which facilitated strong secondary responses upon challenge with
ova antigen. Conclusions: Ligation of TLR2 agonist BLP (Pam3Cys) alone is sufficient to
+ maintain the proliferation of Ova specific CD4 T cells without the need of antigen. Which might
suggest that long-term functional capacities of T cells are set by innate signals during early
phases of an infection