Study on anti-tumor effect of the spleen cells from p185 protein immunized mice
Objective To study the anti tumor effect of p185 oncoprotein as a tumor vaccine. Methods The anti tumor effect in vitro/vivo was studied by using the p185 antigen as a tumor protein vaccine to immunize mice. The splenic lymphocytes from the immunized mice were incubated with p185 tumor antigen for 4 days in vitro, then the supernatant was harvested for detecting the IFN γ activity. The immune splenic lymphocytes in presence of a low dose(10μg/ml)IL 2 containing medium were cultured with p185 antigen for one week and expanded with anti CD3 antibody. The phenotypes of expanded lymphocytes were detected by FACS. The TNF activity secreted by the expanded lymphocyte cells after co incubated with 3T3 neu cells for 4 hours was also tested. 3T3 neu cells with tumorgenicity in nude mice admixed with the expanded lymphocytes (19) in vitro and was then inoculated (s.c.) into nude mice, 3T3 neu cells were inoculated alone or admixed with anti CD3 activated spleen cells (CD3 AK) as control group. Results IFN γ activity in the supernatant was 40.27±9.6U/ml in experimental group(splenocytes from immunized mice), but was undetected in control group (immunized with adjuvant alone). 86.2% expanded lymphocytes were CD3 positive T cells, in which 23% were CD8 positive T cells. The TNF activity was significantly higher in the supernatant from the experimental spleen cells culture than that from control (P0.001). The mean occurrence time of the tumor nodes was 52.5 days in experimental group (among no tumor occurs in 5/6 animals within more than 60 days after inoculation) and 12.5 days or 9.2 days in both control group respectively. The mean survival time of the tumor bearing nude mice was significantly extended in experimented group (55.3 days) than in control group (27.8 days and 25.6 days) respectively. Conclusion These findings indicated that the p185 specific T cells may have an ability to inhibit the 3T3 neu tumor growth in vivo.