Pyrogen from mouse macrophages causes fever in mice

Area of Science:

• Immunology
• Physiology

Background:

• Macrophages play a key role in the immune response.
• Phagocytosis by macrophages can trigger the release of signaling molecules.

Purpose of the Study:

• To investigate the pyrogenic properties of substances released by mouse macrophages.
• To establish a biological assay for endogenous pyrogens using fever response in mice.

Main Methods:

• Stimulated mouse peritoneal macrophage cell culture supernatant was injected intravenously into mice.
• Fever response in mice was monitored in a controlled environment (35°C).
• Properties of the pyrogen were assessed for heat-lability and sensitivity to pronase.

Main Results:

• Intravenous injection of the supernatant induced a rapid, monophasic fever in mice.
• The pyrogen was differentiated from endotoxin.
• The pyrogen exhibited heat-lability and pronase sensitivity, similar to pyrogens from other species.
• Human leucocyte pyrogen elicited identical fever responses in mice.

Conclusions:

• Mouse macrophages release an endogenous pyrogen distinct from endotoxin.
• Fever measurement in mice provides a sensitive bioassay for endogenous pyrogens.
• The pyrogen shares characteristics with endogenous pyrogens from other species.