IL-7 plays an important role in the growth and differentiation of T cells. We have previously reported that IL-7 induces preferential expansion of MHC class I-selected CD4 -CD8 -TCRαβ ⍣ thymocytes which express a skewed V β repertoire and are potent IL-4 producers. In this report, we provide evidence that IL-1 in combination with granulocyte macrophage colony stimulating factor can also expand this population. Yet, these cells do not share the functional characteristics of those obtained in the

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... presence of IL-7, i.e. cytotoxic activity and high IL-4 production. These functional capacities can be acquired by adding IL-7. In conclusion, our findings demonstrate that the capacity of MHC class I-selected CD4 -CD8 -TCRαβ ⍣ thymocytes to produce IL-4 as well as to kill target cells is IL-7 dependent.