Aim: To observe the specific cytotoxic T lymphocyte and humoral immune response induced by MUC1 DNA inmunization in mice.
Methods: Female BALB/c mice were immunized intramuscularly with 100 microg pcDNA3.1-MUC1 3 times at intervals of 3 weeks. Three weeks after the last immunization, tumor challenge experiments were performed by inoculation of MUC1 positive breast cancer cell line EMT6. Both humoral immune response and CTL-specific cytotoxicity were detected by immunohistochemical staining and (51)Cr release assay, respectively.
Results: The cytotoxicity of MUC1-specific CTLs to EMT6 target cells showed that the cytotoxic effect was different at various ratio of effector cells to target cells. At ratios of 100:1, 50:1, 25:1 and 12.5:1, the specific lysis in MUC1cDNA group reached 54.1%, 39.8%, 26.4% and 20.1%, while two control groups 13.2%, 10%, 8.2%, 7.2% and 11.7%, 9.8%, 7.7%, 7.0%, respectively. The former was markedly higher than the two latters(P<0.01). MUC1 expression was exhibited to be positive in breast cancer tissue by immunohistochemical staining with BALB/c mouse sera against MUC1 cDNA. There was only 40% tumorigenic rate in MUC1 cDNA immunized group, while there 100% in pcDNA3.1(+) and NS control groups. There was a significant difference between MUC1 cDNA group and control groups (P<0.05).
Conclusion: Specific CTLs and antibody prodution are elicited by MUC1 DNA inmunization. MUC1 cDNA inmunization partly inhibit the growth of implanted tumor in mice.