RBPJ regulates differentiation and effector programming of intestinal γδ intraepithelial lymphocytes

Intestinal γδ intraepithelial lymphocytes (IELs) are heterogeneous tissue-resident T cells that contribute to epithelial homeostasis and host defense, but the mechanisms regulating their differentiation and functional states remain incompletely understood. Here, we investigated the role of recombination signal binding protein for immunoglobulin kappa J region (RBPJ) in intestinal γδ IELs using mice with CD8 lineage-specific deletion of Rbpj. RBPJ deficiency did not markedly affect the overall proportion of γδ IELs but altered the distribution of Thy1-defined γδCD8αα IEL subsets in the small intestine, increasing Thy1⁺ cells and decreasing Thy1^- cells. Gene expression analysis revealed distinct transcriptional programs, with Thy1^- cells preferentially expressing antimicrobial and epithelial defense-related genes and Thy1⁺ cells expressing lymphocyte-associated and effector genes. RBPJ deficiency reduced Notch-associated gene expression and altered subset-associated transcriptional programs. Competitive transfer experiments demonstrated that these changes were cell intrinsic. RBPJ-deficient γδ IELs also showed altered expression of adhesion-related molecules and reduced granzyme A and B expression. These findings identify RBPJ as a cell-intrinsic regulator of intestinal γδ IEL differentiation and effector programming.