Kinetics of cytokine gene expression during the in vitro CTL induction against a murine nonimmunogenic tumor
Murata, S.; Eguchi, Y.; Mekata, E.; Tani, T.; Kodama, M.
Anticancer Research 20(1a): 363-372
2000
ISSN/ISBN: 0250-7005 PMID: 10769681 Document Number: 516104
Background: The study of the local environment around tumors, including cellular and endogenous cytokine kinetics may improve our understanding of the biological process occurring during the CTL induction. Materials and Methods: The expression kinetics of ten cytokine genes and immune cell subsets were examined by a RT-PCR and immunohistochemistry using a nonimmunogenic murine tumor and its immunogenic variant (A7). Results: In a mixed lymphocyte-parent tumor cell culture (MLTC) using in vivo A7-immunized spleen cells, where CTL induction was confirmed on day 5 of cultivation, IL-6 gene expression was promptly activated at 12 h, IL-2 and IL-4 gene expression was prominently up-regulated on days 1 and 2, and then IL-10 and TGF-beta gene expression was down-regulated from day 2 onward. In contrast, in a MLTC using non-immunized spleen cells (a CTL non-induction model), no prominent up-regulation of the IL-6, IL-2 or IL-4 gene was detected, and expression of the IL-10 and TGF-beta genes increased steadily. Although numerous dendritic cells were observed in the A7 immunized spleen tissue, lower numbers of dendritic cells were evident in the non-immunized spleen tissue. Conclusions: A cellular environment that includes the presence of dendritic cells and a cytokine environment that involves the timely production of IL-6, IL-2, and IL-4, and subsequent inhibition of the immunosuppressive cytokines IL-10 and TGF-beta, appear to play an important role in induction of CTL in this model.