[Effect of the nucleic factor on lymphocyte cytotoxicity]

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Cytotoxicity of lymphocytes plays a crucial role in anti-tumor immunity.
• The Ehrlich tumor is a model for studying tumor-induced immune suppression.
• Understanding immune modulation by tumor-derived factors is key to developing cancer therapies.

Purpose of the Study:

• To investigate the effect of a nucleic factor from Ehrlich tumor ascitic fluid on the in vitro cytotoxicity of lymphocytes from immunized mice.
• To determine if this effect is specific to the nucleic factor or if other nucleic acids elicit a similar response.

Main Methods:

• Isolation of a nucleic factor from Ehrlich tumor ascitic fluid.
• In vitro incubation of lymphocytes from CC57Br mice (immunized with L-cells) with the nucleic factor.
• Assessment of lymphocyte cytotoxicity using splenic and lymph node cells.
• Comparison with the effects of cellular DNA and hepatic RNA from various mouse strains.

Main Results:

• The isolated nucleic factor significantly suppressed the cytotoxicity of both splenic and lymph node lymphocytes from immunized CC57Br mice at concentrations of 5-10 μkm/ml.
• Cellular DNA from non-lineal SHR mice and hepatic RNA from normal C3Ha mice, non-lineal SHR mice, and syngeneic CC75Br mice did not exhibit this suppressive effect at the same concentrations.
• This indicates a specific immunosuppressive activity of the Ehrlich tumor-derived nucleic factor.

Conclusions:

• A specific nucleic factor present in Ehrlich tumor ascitic fluid possesses immunosuppressive properties, reducing lymphocyte-mediated cytotoxicity.
• The observed suppression is not a general effect of nucleic acids but is specific to the factor derived from the tumor.
• These findings highlight a potential mechanism of tumor-induced immune evasion and suggest the factor as a target for further investigation in cancer immunotherapy.