Tumor induction by immunologically activated murine leukemia virus.

Area of Science:

• Immunology
• Oncology
• Virology

Background:

• A graft-vs.-host reaction (GVHR) can be induced in mice.
• Some mice undergoing GVHR develop lymphoreticular tumors.
• The role of murine leukemia virus (MuLV) in GVHR-induced tumors is unclear.

Purpose of the Study:

• To investigate the oncogenic potential of cell-free extracts (CFEs) from GVHR-induced mice.
• To determine if MuLV activation is associated with tumor development.
• To establish a causal link between MuLV and lymphoreticular tumors post-GVHR.

Main Methods:

• Induced GVHR in CAF(I) and CB6F(1) mice using BALB/cJ spleen cells.
• Prepared CFEs from reticular tissues of mice at various times post-GVHR.
• Inoculated newborn syngeneic mice with CFEs to assess tumor induction.
• Tested CFEs for infectious MuLV (XC assay) and complement-fixing (CF) MuLV antigen.

Main Results:

• 41.4% of CFEs from GVHR mice induced lymphoreticular tumors in recipients.
• Oncogenic potential increased significantly (75%) in CFEs from mice 12-15 months post-GVHR.
• Infectious MuLV and CF MuLV antigen were detected in oncogenic CFEs, particularly later after GVHR induction.
• CFEs from normal mice did not transmit tumors or MuLV.

Conclusions:

• MuLV is activated during the GVHR.
• Activated MuLV is responsible for the development of lymphoreticular tumors.
• GVHR serves as a model for MuLV activation and subsequent oncogenesis.