Alloreactive donor effector T cells

Alloreactive donor effector T cells are a specialized population of donor-derived T lymphocytes that recognize non-self major histocompatibility complex (MHC) molecules or minor histocompatibility antigens in a transplant recipient [1]. These cells play a central role in the pathogenesis of Graft-versus-Host Disease (GvHD) and allograft rejection, where they undergo activation, proliferation, and infiltration into host tissues such as the skin, liver, and gastrointestinal tract [4, 6]. Once activated, they secrete pro-inflammatory cytokines, such as interferon-gamma and tumor necrosis factor-alpha, and employ cytolytic mechanisms like the perforin/granzyme pathway to cause host tissue injury [5, 8]. Therapeutic interventions aim to selectively deplete these cells, inhibit their activation via costimulation blockade, or suppress their effector functions using immunosuppressive agents like calcineurin inhibitors [1, 9]. A major challenge in targeting these cells is maintaining the beneficial graft-versus-tumor (GVT) effect, as broad suppression or depletion can increase the risk of cancer relapse and opportunistic infections [6, 7]. Consequently, modern strategies often focus on the selective elimination of activated alloreactive clones while sparing regulatory T cells or non-alloreactive memory cells [2, 4].

Other names

Donor-reactive T cellsAlloreactive T cellsHost-reactive donor T cellsAlloreactive effector T cells

Therapeutic agents target these cells through various mechanisms, including direct lymphodepletion (e.g., anti-thymocyte globulin), selective elimination of proliferating clones (e.g., post-transplant cyclophosphamide), inhibition of intracellular signaling pathways like the calcineurin-NFAT pathway (e.g., tacrolimus), and blockade of costimulatory signals required for T-cell activation (e.g., abatacept).