A viral immunodepressive factor associated with experimental mouse tumors

Area of Science:

• Immunology
• Virology
• Oncology

Background:

• Transplantable mouse tumors can produce factors that suppress the host's immune response.
• Understanding these factors is crucial for managing transplant rejection and cancer progression.

Purpose of the Study:

• To detect and characterize an immunodepressive factor (IDF) from mouse tumors.
• To investigate the biological properties and potential viral nature of IDF.
• To explore the relationship between IDF and host allograft reactivity.

Main Methods:

• Detection of IDF in transplantable mouse tumors.
• Administration of IDF to mice and assessment of allograft reactivity over time.
• In vitro replication studies in mouse, rat, and HeLa cell cultures.
• In vitro inactivation studies using heat, UV light, ether, and alcohol.
• Serological analysis for IDF-titer and persistence.

Main Results:

• IDF inhibited allogeneic lymphoma rejection in mice, impairing host allograft reactivity for at least 10 months.
• IDF persisted in mouse sera for over 3 months, with no activity in rats.
• IDF replicated in vitro in mouse embryo cells but not in rat or HeLa cells.
• IDF was inactivated by heat, UV light, and ether, but not alcohol.
• A potential association between IDF and lactic dehydrogenase virus was observed.

Conclusions:

• IDF is likely a virus causing long-lasting, asymptomatic infection that specifically interferes with host allograft reactivity.
• IDF's properties suggest a role in immune evasion for tumors.
• Further research is needed to confirm the identity of IDF and its relationship with lactic dehydrogenase virus.