American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which inflammatory mediator increases during the acute phase response?

1. TNF-alpha

2. IL-6

3. IL-10

4. IFN-gamma

The correct answer is: IL-6

During the acute phase response, IL-6 plays a crucial role as an inflammatory mediator. It is produced predominantly by macrophages and fibroblasts in response to infection or injury. IL-6 is responsible for stimulating the acute phase proteins, such as C-reactive protein (CRP), produced by the liver, which are essential for the body's initial response to inflammation and infection. The elevation of IL-6 during this phase helps to modulate the immune response, promoting fever and enhancing the production of acute phase reactants. This response is vital for coordination of the body's defense mechanisms, making IL-6 a key player in the acute phase response. In contrast, other inflammatory mediators listed here exhibit differing roles or may not be as heavily elevated during the acute phase response. For instance, TNF-alpha is also an important mediator in inflammation, but its spike is generally more pronounced in specific contexts rather than as a primary component of the acute phase response. IL-10 is an anti-inflammatory cytokine that works to downregulate the immune response, and IFN-gamma is primarily involved in the adaptive immune response, particularly in activating macrophages. Therefore, IL-6's significant increase aligns perfectly with the mechanisms we observe in the acute phase response