Why Do We Get Fevers? It’s More Than Just “Heat Kills Bugs.”

Dr. Jeffery Rathmell published a study in Science Immunology on how fever-like temperatures alter immune cell behavior, enhancing the activity of key infection-fighters while reducing suppression in regulatory cells by changing their metabolism. This process might also contribute to the invcreased cancer risk linked to chronic inflammation, revealing ‘the darker side of our immune response’.

‘A little bit of fever is good, but a lot of fever is bad.’

Author: Darren Heintzman, Rachael Sinard, Kimryn Rathmell, John Wilson, Jeffrey Rathmell. 

Published in Science Immunology in September 2024

Fevers are an essential part of the body’s defense system, often arising as a response to infections. The article from Popular Science delves into why fevers occur and how they benefit immune function, offering insights into their complexities.

Fever’s Purpose in Immunity

Traditionally, fevers have been viewed as a straightforward response to infections, aimed at “cooking” the pathogens. However, science now shows that the body’s elevated temperature during a fever serves a more intricate role. By raising the body temperature, immune cells become more efficient. Lymphocytes, macrophages, and other components of the immune system operate optimally at higher temperatures, actively recognizing and attacking pathogens. Fevers also impede the replication of viruses and bacteria, slowing their spread throughout the body. For these reasons, mild to moderate fevers can enhance the body’s capacity to eliminate infections.

Boosting Immune Function

A fever doesn’t merely raise body temperature; it triggers the release of heat-shock proteins, which protect cells from the stress caused by elevated heat. These proteins also assist in cell repair and contribute to the immune response. At higher temperatures, certain immune cells, such as neutrophils and macrophages, show increased phagocytic activity. Phagocytosis, the process by which immune cells engulf and digest foreign particles, is significantly enhanced during fevers, allowing the body to target and break down infections more effectively.

Fevers: When They Become Harmful

While fevers can be helpful, the article warns about the risks associated with excessively high or prolonged fevers. When body temperature exceeds 40°C (104°F), it can begin to damage cells. Proteins may denature, and the body’s enzymes might malfunction, leading to organ stress or failure in severe cases. Chronic fevers, often resulting from autoimmune disorders or long-term inflammation, can contribute to cellular stress and potentially worsen certain health conditions. Medical intervention, such as fever-reducing medications, is often recommended when fevers are too high, as they can reduce the risk of damage while the body fights off the infection.

Fevers Beyond Infection

Although commonly associated with infections, fevers can also occur due to conditions like cancer. In oncology, fevers might be the body’s response to tumors or the result of chemotherapy treatments, which suppress the immune system. Fevers in cancer patients can be a sign of neutropenia, a condition where low white blood cell counts make patients more vulnerable to infections. The article touches on how medical treatments, such as fever-reducing drugs or antibiotics, are vital for managing fever in such immunocompromised patients.