Alloreactive donor T-lymphocyte population (Alloreactive T cells)

The alloreactive donor T-lymphocyte population consists of mature T cells present in a donor graft that recognize the recipient's human leukocyte antigens (HLA) or minor histocompatibility antigens as foreign (PMID: 28235555). Upon recognition, these cells undergo rapid activation, clonal expansion, and differentiation into effector cells that infiltrate and damage host tissues, such as the skin, liver, and gastrointestinal tract (StatPearls: Graft Versus Host Disease). This process is the fundamental pathophysiology underlying graft-versus-host disease (GVHD), a major complication of allogeneic hematopoietic stem cell transplantation. While these cells are responsible for harmful GVHD, they also contribute to the beneficial graft-versus-leukemia (GVL) effect by eliminating residual malignant cells (PMID: 28235555). Pharmacological interventions typically target this population through broad immunosuppression using calcineurin inhibitors or antimetabolites, or through more selective methods like post-transplant cyclophosphamide or ex vivo T-cell depletion (PMID: 30655272). Modern therapeutic goals focus on selectively eliminating alloreactive clones while preserving regulatory T cells and pathogen-specific immunity to reduce the risk of infection and disease relapse (PMID: 23160470).

Other names

Donor alloreactive T cellsGraft-versus-host reactive T cellsAllospecific T cellsHost-reactive donor T cellsAlloreactive T-lymphocytes

Therapeutic strategies target this population through several mechanisms: calcineurin inhibitors and mTOR inhibitors prevent T-cell activation and signaling; antimetabolites inhibit the proliferation of activated clones; polyclonal and monoclonal antibodies cause direct depletion; and post-transplant cyclophosphamide selectively eliminates rapidly dividing alloreactive cells while sparing regulatory T cells.