CD70 identifies donor derived alloreactive T cells in severe acute Graft vs Host Disease post allogeneic SCT

Graft-versus-host disease (GvHD) remains a major challenge post allogeneic hematopoietic stem cell transplantation (allo-HSCT) and understanding its immunopathology is crucial for effective therapeutic intervention. Here we investigated the significance of CD70, a co-stimulatory molecule, in the context of aGvHD. CD70 was found to be transiently expressed on activated T cells during early immune reconstitution post-transplantation but persisted longer in aGvHD. Our findings illustrate that CD70+ T cells are characterized by upregulated activation receptors and enhanced cytokine production, while displaying signs of exhaustion. Remarkably, CD70+ T cells expressed chemokine receptors CCR4 and CCR6 and were actively recruited to inflamed tissues, implicating them in aGvHD pathogenesis. The chromatin at transcription factor MGA and NFAT5 loci was found to be selectively altered upon allo-antigenic stimulation in CD70+ T cells ex-vivo. Gene transcriptions of Toll-like receptors and MAPK signalling pathway were also found to differ in CD70+ and CD70- T cells of aGvHD patients. Insights into the clonality and antigen specificity of CD70+ T cell populations revealed potential novel antigenic targets. Further blocking CD70 in allogeneic T cells from aGvHD patients primed with autologous antigen presenting cells prior to HSCT demonstrated that anti-CD70 antibody reduced T cell proliferation and cytokine production. These findings implicate CD70 as a potential therapeutic target to modulate T cell responses and mitigate aGvHD. Targeting the CD70-CD27 co-stimulation pathway holds promise for prophylactic treatment.