[Massive apoptosis in P815 mastocytoma in vivo induced by interleukin 2 gene transduction].
A study was carried out to determine the mechanisms of the P815 murine mastocytoma rejection. IL2 gene was transferred into the P815 mastocytoma cells by the retroviral vector. The transduced cells were selected with G418 (1 mg/ml). The single P815/IL2 cells were obtained through the limit dilution method. Using digoxigenin-labelled IL2 cDNA as the probe, IL2 mRNA expression was detected by in situ hybridization. The activity of IL2 dependent cell line in the cultural medium of P815/IL2 cells was assayed by MTT Color reaction with 30-147 U/ml per 10(6) cells every 24 hours. The detection of the proliferation activity indicated that P815/IL2 cells grew slower than the parental cells. IL2 gene modified P815 mastocytoma cells were inoculated into DBA/2 mice. The results showed that parental P815 cells produced tumors in 100% DBA/2 mice about 5-6 days after injection and grew progressively, but P815/IL2 tumor cells did not grow at all or did much later and completely regressed after a transient growth in mice. The ultrastructural studies indicated that the P815/IL2 cells in vivo had changed remarkably. The heterochromatin was increased and nuclei became irregular in shape. Immature and mature special granules appeared near the Golgi's complexes. The most impressive findings were massive apoptosis in the tumor tissues. Massive apoptosis must be specific for IL2 gene transduction, because it was not found in tumors produced by the parental cells. Apopotic cells were phagocytosed by macrophages and nearby tumor cells. Various cell infiltration, composed predominantly of eosinophils and macrophages were seen in the tumor tissue. The results suggested that the difference in differentiation of P815/IL2 cells in vivo might be induced by factors from the host. Tumor rejection may be the result of the multi-cell-mediated reaction including eosinophils, macrophages and other host cells.
Guo
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Institute of Basic Medical Sciences, Chinese Academy of Military Medical Sciences, Beijing.
Li
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Liu
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D000818:Animals; D017209:Apoptosis; D005260:Female; D018014:Gene Transfer Techniques; D007376:Interleukin-2 / Q000235:genetics*; D012515:Mast-Cell Sarcoma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D012333:RNA, Messenger / Q000096:biosynthesis; D014407:Tumor Cells, Cultured
D007376:Interleukin-2; D012333:RNA, Messenger