The IL-17A ELISPOT in organ transplantation

In the organ transplantation field, the ELISPOT assay is used as a reliable tool as guide for therapeutic interventions after transplantation. Different studies have shown that the number of IFN-γ producing T cells correlate with post transplantation outcome. For example, an increased frequency of donor-specific IFN-γ producing cells before transplantation was related to the risk of acute rejection and impaired post transplant function.

Additionally, the assay has high value in immune monitoring of alloreactivity after reduction or withdrawal of immunosuppressive drugs and identifying patients tolerant to their allograft.

Some studies have suggested the involvement of IL-17 in human allograft rejection. Naïve human CD4 T cells can differentiate into Th17 cells, secreting the pro-inflammatory cytokines IL-17A and IL-22. Th17 cells express CCR4, CCR6 and STAT4 and are clearly pathogenic, thereby challenging the importance of classical Th1 cells in the induction and maintenance of chronic inflammatory disease.  As a result of these properties, the IL-17 family has been linked to various immune/autoimmune related diseases including rheumatoid arthritis, asthma, lupus, anti-tumor immunity, and also allograft rejection. Recently, Van Besouw et al. (2015) measured the frequency of IL-17A producing cells reactive to donor cells in peripheral blood mononuclear cells (PBMC) of heart transplant patients with U-Cytech’s IL-17A ELISPOT assay (CT416). The authors demonstrated circulating donor-reactive IL-17A producing cells only during immunologic quiescence (without acute rejection [AR]), and not in PBMCs collected from heart transplant recipients with early (≤ 3 months) or late (> 3 months) AR.  

Van Besouw et  al. (2015). Interleukin-17-producing CD4+ cells home to the graft after human heart transplantation. J Heart Lung Transplant (34; 7:933-940).