ABSTRACT
AIM: To study the effects of cholecystokinin octapeptide (CCK-8) on T-lymphocyte subsets in keyhole limpet haemocyanin (KLH)-immunized mice.METHODS: Female BALB/c mice were immunized with KLH and injected with different dosages of CCK-8 or saline simultaneously. Positive CD4+and CD8+ T cells in peripheral blood or splenocytes were measured by flow cytometry. The production and mRNA level of Th1 cytokine, IFN-? and Th2 cytokine, IL-4 in the splenocytes were evaluated by ELISA and RT-PCR, respectively. In addition, lung tissue sections were made with HE staining.RESULTS: CCK-8 downregulated the positive CD4+and CD8+ T lymphocytes both in peripheral blood and in splenocytes in KLH-immunized mice, resulting in the reduction of CD4+/CD8+ ratio.CCK-8 improved the production of IFN-?, elevated IFN-? gene transcription, whereas cut down the production of IL-4, decreased IL-4 gene transcription. CCK-8 lightened the pulmonary inflammation induced by KLH.CONCLUSION: CCK-8 inhibits CD4+T lymphocytes activation, Th2 cytokine mRNA expression and protein production in KLH-immunized mice, indicating that CCK-8 modulates adaptive immune response.