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Lack of distinctive surface antigen on cells transformed by murine sarcoma virus
Abstract:
Some murine sarcoma virus (MSV)-transformed mouse 3T3 cells contain the MSV genome in the absence of infectious helper murine leukemia virus (MuLV) and MSV production. These cells, designated S+L- (sarcoma positive, leukemia negative), were analyzed for the presence of a possible MSV-determined membrane antigen by the mixed hemadsorption test and in vitro lymphocyte cytotoxicity assay. Two different serological approaches were used: (a) isoantibody-free sera were obtained by immunizing with MSV of syngeneic origin or by allowing primary, autologous MSV sarcomas to regress, or (b) alloantisera obtained by immunizing C57BL mice with S+L- cells were absorbed with the corresponding nontransformed 3T3 cells until all activity against 3T3 had been removed. While MuLV-superinfected S+L- cells and a culture line of an MSV sarcoma known to produce both MSV and MLV were highly reactive, normal 3T3 and S+L- cells were negative. Similarly, lymph node cells from MSV immune mice or rats did not kill S+L- cells, although they were cytotoxic against target cells known to carry MuLV-associated antigens. Thus, the present study gives no positive evidence for the existence of any MSV-induced new surface antigen in the transformed target cell, known to carry the viral genome.
Insights
This study investigated murine sarcoma virus (MSV)-transformed cells for new surface antigens. Researchers found no evidence of MSV-induced antigens on these S+L- cells, despite them carrying the MSV genome.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Murine sarcoma virus (MSV)-transformed mouse 3T3 cells (S+L-) can harbor the MSV genome without producing infectious virus.
- The presence of MSV-specific surface antigens on these transformed cells has been hypothesized.
Purpose of the Study:
- To investigate the existence of MSV-determined membrane antigens on S+L- cells.
- To determine if transformed cells carrying the MSV genome express new surface antigens.
Main Methods:
- Utilized mixed hemadsorption tests and in vitro lymphocyte cytotoxicity assays.
- Employed serological approaches including isoantibody-free sera and absorbed alloantisera.
- Tested reactivity against MSV-transformed cells, normal 3T3 cells, and MuLV-superinfected cells.
Main Results:
- S+L- cells and normal 3T3 cells showed no reactivity in serological tests.
- Lymphocyte cytotoxicity assays did not demonstrate cell killing of S+L- cells by immune cells.
- Control cells (MuLV-superinfected S+L- and MSV sarcoma line) exhibited expected reactivity.
Conclusions:
- The study found no positive evidence for MSV-induced new surface antigens on S+L- cells.
- Transformed cells carrying the MSV genome did not display detectable MSV-specific membrane antigens using the methods employed.
- Further investigation may be needed to explore other potential markers or mechanisms.