Kinetics of lymphocyte subpopulations in allogeneic grafted scales of ginbuna crucian carp

• Rejection of allogeneic scale grafts occurred 3 days after transplantation.
• CD4+ T cells were detected as early as 3 days after transplantation.
• CD8α+ T cell counts were highest at 3 days post-transplantation and they accumulated on the border of the grafted scales.
• Both CD4+ and CD8α+ T cells may play major roles in allogeneic rejection.
• Other cell types such as sIgM+ cells or phagocytic cells also may contribute to allograft rejection.

In mammals the rejection of allografts is primarily accomplished by cell-mediated immunity including T cells. Recently, considerable studies reveal the existence of helper and cytotoxic T cell subsets in fish. Here we investigate the kinetics of CD4+ and CD8α+ T cells along with sIgM+ cells and phagocytic cells in an allogeneic scale graft model using ginbuna crucian carp for understanding the mechanisms of cell-mediated immune response. The results showed that CD4+ T cells first infiltrated into allogeneic scales followed by CD8α+ and sIgM+ cells, and finally phagocytic cells appeared in the graft. Furthermore, most of the CD8α+ T cells appeared on the border of the allografted scales at the time of rejection. These results suggest that T cells play crucial roles and work together with other cell types for completion of allograft rejection.

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