Staphylococcal enterotoxin B (SEB) primarily affects what part of the body?

Staphylococcal enterotoxin B (SEB) primarily affects the immune system because it acts as a superantigen, leading to an abnormal activation of T cells. This results in a massive release of pro-inflammatory cytokines, which can lead to a variety of symptoms associated with toxic shock syndrome. This hyperactivation causes overwhelming immune responses, affecting the body’s ability to regulate inflammation effectively.

The mechanism of SEB involves its binding to major histocompatibility complex (MHC) class II molecules and T cell receptors, which is distinctive to superantigens. This inappropriate stimulation can lead to serious health issues, including fever, shock, and organ failure due to systemic inflammatory responses.

In contrast, while SEB can have secondary effects on other systems through the immune response, its primary action and the resulting consequences are closely tied to immune system dysfunction, making it the correct answer in this context.