Deconvoluting alloimmunity in time and space through Serial Intravascular Staining: Evidence for rapid donor tissue-resident memory T cell resident memory formation during gastrointestinal GVHD.

Here we have applied Serial Intravascular Staining (‘SIVS’), complemented by single cell transcriptomic analysis, to ascertain the time-, tissue- and donor-dependence of T cell infiltration-mediated immune pathology during aGVHD in a non-human primate (NHP) model. We demonstrate rapid differentiation of donor tissue-infiltrating CD8 T cells in situ into tissue-resident memory T cells (TRM), coincident with destruction of aGVHD target tissues. We also combined SIVS with single cell RNA Sequencing (scRNASeq) to identify the transcriptional programs controlling these actively infiltrating cells. Examination of transcriptomes of individual colon cells in non-human primate (NHP) model of aGVHD