Aim: To analyze the relationship between Nrp-1(neuropilin-1) positive T cells (Nrp-1(+)T cells) and CD4(+)CD25(+) regulatory T cells (CD4(+)CD25(+)Treg) and compare their immunoregulatory effects.
Methods: The expression of Nrp-1, CD4 and CD25 on the splenic T cells of BALB/c mice was detected by flow cytometry and Nrp-1(+)T cells and CD4(+)CD25(+)Treg were sorted. Then their effects of on NK cells killing B16-F10-luc-G5 melanoma cells were compared in vitro by bioluminescence imaging system.
Results: The expression of Nrp-1 on CD4(+)CD25(+)Treg was (27.28+/-1.17)%, which was significantly higher than that (1.63+/-0.08)% on CD4(+)CD25(-) T cells(P<0.01). Both Nrp-1(+)T cells and CD4(+)CD25(+)Treg inhibited the effect of killing NK cells on B16-F10-luc-G5 melanoma cells in vitro. At 6, 24, 48 and 72 h, the number of tumor cells in Nrp-1(+)T cell group was higher than that in CD4(+)CD25(+)Treg group(984+/-15 vs 931+/-4, 1015+/-14 vs 983+/-8, 1261+/-21 vs 1201+/-18 and 1323+/-38 vs 1256+/-18, respectively). There was significant statistical difference between the two groups at each time point (P<0.01).
Conclusion: The proportion of CD4(+)CD25(+)Treg expressing Nrp-1 is high. Nrp-1(+)T cells show negtive immunoregulatory effect, which is more powerful than CD4(+)CD25(+)Treg. Nrp-1(+)T cells may be regarded as a new subgroup of Treg.