Expression of Neuropilin-1 In Kidney Graft Biopsies: What Is the Significance?

Abstract Objective Recent work has suggested that neuropilin-1 (NRP-1) is a surface marker of regulatory T cells (Treg). However, no further relative evidence has been provided to confirm this finding. Since Treg should decline during rejection, the expression of NRP-1 on lymphocytes should decline in a rejected graft. To test this proposal, we examined NRP-1 expression in kidney graft biopsies. Materials and Methods Tissue samples were obtained from 20 kidney graft biopsies with pathologically confirmed acute rejection and from 10 without rejections. We performed immunohistochemistry assays using an anti-NRP-1 monoclonal antibody. The positive cells were counted and the ratios among lymphocytes analyzed. Results Compared with samples from nonrejected graft biopsies (18.71 ± 20.60), the number of positive cells among lymphocytes in the rejected samples showed a lower percentage (3.16 ± 1.72; P < .05). Conclusions NRP-1 has an important role in directing the growth of nervous synapses and immune synapses. We found in rejected grafts that the percentage of NRP-1 positive cells among lymphocytes decreased significantly. Therefore, NRP-1 may have a previously unrecognized role to predict the immune state of the graft as a potential marker for Treg.