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Wednesday, November 9, 2011

Don’t treat a fever

We seem to have a temperature theme going here. Yesterday cooling, today, heating for better health.  A slightly higher body temperature not only makes it more difficult for microbes to replicate, but also enhances key components of our immune systems.  Researchers from the Roswell Park Cancer Institute found that raising the core body temperature of mice by two degrees Celsius before exposing them to an antigen preferentially increased the number of CD8+ immune cells that could respond to that antigen.

CD8+ cells (also known as cytotoxic or killer T cells) are a type of lymphocyte or white blood cell whose job it is to kill infected cells.  Briefly, a cell that has been infected by a virus or bacteria will present bits of that microbe on its surface. Those antigens then interact with receptors on the membranes of T cells such as CD8+ cells.  This interaction results in both proliferation and activation of the immune cells, which then release cytotoxic (cell-killing) compounds. Increasing the body temperature of mice led to an increase in the number of activated CD8+ cells, possibly due to tiny changes in the lymphocytes’ cell membranes.

It’s not surprising that a slight fever can be beneficial to an animal suffering from an infection.  Many animals will deliberately raise their temperatures when ill.  Now we know why, namely that a higher body temperature can have a direct and positive effect on the immune system.  That said, the authors caution that very high fevers should still be treated.