KLF13 sustains thymic memory-like CD8(+) T cells in BALB/c mice by regulating IL-4-generating invariant natural killer T cells.

"Memory-like T cells" are a subset of thymic cells that acquire effector function through the maturation process rather than interaction with specific antigen. Disruption of genes encoding T cell signaling proteins or transcription factors have provided insights into the differentiation of such cells. In this study, we show that in BALB/c, but not C57BL/6, mice, a large portion of thymic CD4(-)CD8(+) T cells exhibit a memory-like phenotype. In BALB/c mice, IL-4 secreted by invariant natural killer T (iNKT) cells is both essential and sufficient for the generation of memory-like T cells. In C57BL/6 mice, iNKT cells are less abundant, producing IL-4 that is insufficient to induce thymic memory-like CD8(+) T cells. BALB/c mice deficient in the transcription factor Kruppel-like factor (KLF) 13 have comparable numbers of iNKT cells to C57BL/6 mice and extremely low levels of thymic memory-like CD8(+) T cells. This work documents the impact of a small number of KLF13-dependent iNKT cells on the generation of memory-like CD8(+) T cells.