Author(s): Rubinstein MP, Kovar M, Purton JF, Cho JH, Boyman O,
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Abstract IL-15 is normally presented in vivo as a cell-associated cytokine bound to IL-15Ralpha. We show here that the biological activity of soluble IL-15 is much improved after interaction with recombinant soluble IL-15Ralpha; after injection, soluble IL-15/IL-15Ralpha complexes rapidly induce strong and selective expansion of memory-phenotype CD8(+) cells and natural killer cells. These findings imply that binding of IL-15Ralpha to IL-15 may create a conformational change that potentiates IL-15 recognition by the betagamma(c) receptor on T cells. The enhancing effect of IL-15Ralpha binding may explain why IL-15 normally functions as a cell-associated cytokine. Significantly, the results with IL-2, a soluble cytokine, are quite different; thus, IL-2 function is markedly inhibited by binding to soluble IL-2Ralpha.
This article was published in Proc Natl Acad Sci U S A
and referenced in Advancements in Genetic Engineering