(A) Freshly isolated CD4+CD25−Nrp1+ T cells (105, C57BL/6) were co-cultured with syngeneic responder CD4+CD25− T cells (C57BL/6) in different ratios (0, 1∶8, 1∶4, 1∶2, 1∶1) in order to address stimulation induced by irradiated BALB/c (donor) splenocytes (105). Cell proliferation was determined by 3H thymidine incorporation. (B) Cytokine content of the MLRsup where the suppressor cell versus CD4+CD25− T cell was 0 (CTR) and 1∶1 (Nrp1) was evaluated by ELISA. Results are presented as mean ± SD values of triplicate wells, and are representative of 3 independent experiments. *P<0.05, **P<0.01, ***P<0.001. Nrp1 = neuropilin-1, MLRsup = mixed-lymphocyte reaction supernatants, CTR = control group, 3H-TdR = metabolic incorporation of tritiated thymidine, cpm = cells per million, NS = not significant.