ABSTRACT
OBJECTIVE To evaluate whether the IDO1 inhibitor 1- methyl- L- tryptophan (1- MT) combine calcium influx inhibitor carboxyamidotriazole (CAI) could further enhance the suppression of programmed death 1 (PD-1) in CD8 + T cells and investigate the curative effect of the combined use. METHODS CD8 +T cells were isolated from normal mice spleen by negative selection using magnetic cell separation. The isolated CD8 +T cells were cultured in RPMI 1640 medium containing 10% FBS and 100 U·mL- 1 IL-2 and activated by the addition of anti-CD3 and anti-CD28 (1 g·L- 1 each mabs). CD8 + T cells were pretreated for 48 h with drug and the fluo- 3 as a marker of intracellular calcium concentration was detected by flow cytometry. The calcineurin (CaN) levels were assayed with ELISA in CD8+T cells after 48 h incubation with 10 μm CAI. The nuclear translocations of NFAT and AHR were detected by immunofluorescent staining after 48 h of drug treatment. The expression of PD-1 in CD8+T cells was analyzed by flow cytometry. RESULTS Intracellular fluorescent intensity was markedly debase due to CAI treatment(P<0.01). Meanwhile, the changes of CaN content had a resembled correlation (P<0.01). Immunofluorescence experiment showed that after combination therapy the transfer of NFAT and AHR in nuclear substantially reduced. Flow cytometry revealed that after the combination caused a significant decrease in PD-1 expression in CD8+T cells. CONCLUSION CAI and 1-MT could inhibit markedly the expression of PD-1 in CD8 +T cells by inhibiting the nuclear translocation of NFAT and AHR, respectively and the combination of them has synergetic effect.