ID3 and infection: scRNA sequencing experiments revealed the functional heterogeneity of tissue-resident CD8αβ+ T cells (56) with a resident subpopulation of Blimp1hi Klrg1hi/int CD127 small intestinal IEL which dominate early after systemic LCMV (i.p) infection to become tissue-resident effector memory cells, whereas Id3+ KLRg1lo CD127hi cells represented tissue-resident memory precursor cells, which later become tissue-resident memory cells.