Type 17 CD8+ T cells display enhanced antitumor immunity.

Interleukin-17 (IL-17)-secreting CD8(+) T cells have been described, but they have not been thoroughly studied and they do not have a known role in cancer immunotherapy. We skewed CD8(+) T cells to secrete IL-17 through priming in Th17-polarizing conditions. IL-17-producing CD8(+) T cells demonstrated reduced expression of Eomes and diminished cytolytic differentiation in vitro. However, after adoptive transfer, these cells converted to interferon-gamma-producing effector cells and mediated regression of large, established tumors. This improved antitumor immunity was associated with increased expression of IL-7R-alpha, decreased expression of killer cell lectin-like receptor G1, and enhanced persistence of the transferred cells. This report is the first description of a cancer therapy with IL-17-secreting CD8(+) T cells. These findings have implications for the improvement of CD8(+) T cell-based adoptive immunotherapy.

Evolution and survival of marine carnivores did not require a diversity of killer cell Ig-like receptors or Ly49 NK cell receptors.

Ly49 lectin-like receptors and killer cell Ig-like receptors (KIR) are structurally unrelated cell surface glycoproteins that evolved independently to function as diverse NK cell receptors for MHC class I molecules. Comparison of primates and various domesticated animals has shown that species have either a diverse Ly49 or KIR gene family, but not both. In four pinniped species of wild marine carnivore, three seals and one sea lion, we find that Ly49 and KIR are each represented by single, orthologous genes that exhibit little polymorphism and are transcribed to express cell surface protein. Pinnipeds are therefore species in which neither Ly49 nor KIR are polygenic, but retain the ancestral single-copy state. Whereas pinniped Ly49 has been subject to purifying selection, we find evidence for positive selection on KIR3DL during pinniped evolution. This selection, which focused on the D0 domain and the stem, points to the functionality of the KIR and most likely led to the sea lion's loss of D0. In contrast to the dynamic and rapid evolution of the KIR and Ly49 genes in other species, the pinniped KIR and Ly49 have been remarkably stable during the >33 million years since the last common ancestor of seals and sea lions. These results demonstrate that long-term survival of placental mammal species need not require a diverse system of either Ly49 or KIR NK cell receptors.