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Species specificity of guinea pig and human lymphotoxin colony inhibitory activity
Abstract:
The species specificity of lymphotoxin colony inhibitory activity was measured by in vitro colony growth of neoplastic and nonneoplastic cells in the presence of lymphotoxin from the same or from a xenogeneic species. Growth of guinea pig, rat, and mouse neoplastically transformed cells was inhibited by guinea pig lymphotoxin. Colony formation of benzo(a)pyrene transformed 104C1 guinea pig cells was inhibited 45% with lymphotoxin at 42 units/ml medium; nontransformed 104 and 118 guinea pigs cell were not inhibited. Alpha L929, a spontaneously transformed mouse cell, was completely inhibited. Dimethylbenz(a)anthracene (DMBA) 3T3-D and R4-2 mouse transformed cells were inhibited 40 and 100%, respectively, but parental nontransformed 3T3 cells were not inhibited. DMBA transformed R-2 and R-6 rat cells were inhibited 20 and 40%, respectively, but secondary nontransformed fetal rat cells were unaffected. In contrast, normal human xeroderma pigmentosum, Lesch-Nyhan and 1220 fibroblast cells were inhibited 50-60%. No inhibition of HeLa or RPMI 2650 human tumor cells occurred. HeLa and RPMI 2650 cells, however, were inhibited 30 and 60%, respectively, by human lymphotoxin, but normal human and tumorigenic guinea pig cells were unaffected. Thus, guinea pig and human lymphotoxin exhibit species specific and differential cytotoxicity mechanisms for normal and tumor cells.
Insights
Guinea pig and human lymphotoxin show species-specific activity, inhibiting tumor cell growth but sparing normal cells. This suggests differential cytotoxicity mechanisms are at play for various cell types.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Lymphotoxin (LT) is a cytokine involved in immune responses and cell death.
- Understanding LT's species specificity is crucial for its therapeutic potential.
Purpose of the Study:
- To investigate the species specificity of lymphotoxin's colony inhibitory activity.
- To determine if lymphotoxin exhibits differential cytotoxicity against neoplastic and nonneoplastic cells.
Main Methods:
- In vitro colony growth assays were performed using neoplastic and nonneoplastic cells.
- Cells were exposed to lymphotoxin from either the same or a xenogeneic species.
Main Results:
- Guinea pig lymphotoxin inhibited growth of guinea pig, rat, and mouse neoplastic cells, but not normal cells.
- Human lymphotoxin inhibited human tumor cells (HeLa, RPMI 2650) but not normal human or guinea pig cells.
- Normal human fibroblast cells showed 50-60% inhibition by guinea pig lymphotoxin.
Conclusions:
- Lymphotoxin exhibits species-specific inhibition of neoplastic cell growth.
- Differential cytotoxicity mechanisms are employed by lymphotoxin against normal and tumor cells.
- LT's activity is dependent on the species of origin and the target cell type.