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Cutting edge: precursor frequency affects the helper dependence of cytotoxic T cells
Justine D Mintern1, Gayle M Davey, Gabrielle T Belz
1Immunology Division, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville 3050, Victoria, Australia.
Abstract:
Generation of CTL immunity often depends on the availability of CD4 T cell help. In this report, we show that CTL responses induced by cross-priming can be converted from CD4-dependent to CD4-independent by increasing the frequency of CTL precursors. In the absence of CD4 T cells, high numbers of CTL precursors were able to expand in number and become effector CTL. The ability of high frequencies of CD8 T cells to override help was not due to their ability to signal CD40 via expression of CD154. These findings suggest that when precursor frequencies are high, priming of CD8 T cell responses may not require CD4 T cell help.