Conversely, increased IL-7 and IL-15 can expand memory T cells, including pathogenic tissue-resident memory T cells, as seen in lymphopenia and certain chronic-inflammatory disorders and malignancies.
Thus, T cells expressing low-avidity TCR responded poorly to IL-15/IL-15Rα complex, which correlated with a poor homeostatic proliferative response to lymphopenia.
In keeping with the known roles of IL-2 and IL-15 in the development of NK and CD8 T cells in the mouse model, these data suggest that an impaired, but not abolished, survival response to IL-2 and IL-15 accounts for the persistent lack of NK cells and the transient CD8 alphabeta T lymphopenia documented in vivo.