The characteristics of TCRVα24+ NKT cells in response to in vitro stimulation

AIM: To investigate the amount and patterns of expressing CD69, IL-4 and IFN-γ on TCRVα24⁺ NKT cells, and compare with that of CD3⁺ T cells from human peripheral blood in response to in vitro stimulation. METHODS: The whole blood was stained with three-color immunofluorescence directly or after cultured with PDB+ionomycin (Ion) for 6 h, then the mononuclear cells were separated by lysing red blood cells. The expression rates of CD69, IL-4 and IFN-γ on TCRVα24⁺ NKT cells and CD3⁺ T cells were estimated by flow cytometer. RESULTS: As a proportion of mature T cells, the ratio of TCRVα24⁺ NKT cells to CD3⁺ T cells was about (1.34±0.42)%. The expression rates of CD69 on TCRVα24⁺ NKT cells and CD3⁺T cells in response to PDB+Ion for 6 h were (96.71±1.33)% and (98.60±0.47)%, respectively, while the ratio were (11.47±2.86)% and (1.07±0.45)% in the unstimulated group, and there were significant difference between them. The expression rates of IL-4 and IFN-γ on TCRVα24⁺ NKT cells stimulated with PDB+Ion for 6 h were (48.62±2.44)% and (46.65±8.91)%, respectively, which were significantly higher than that of unstimulated group (31.57±3.31)%, (13.45±6.29)%] and that of stimulated CD3⁺ T cells, though the expression rates on stimulated CD3⁺ T cells were significantly higher than that of unstimulated CD3⁺ T cells. CONCLUSION: There is small amount of NKT cells in adult human peripheral blood. The expression rates of IFN-γ and IL-4 on these lymphocytes are higher than CD3⁺ T cells, suggesting that NKT cells are important immunomodulatory cells in special microvironments.