What is the primary effect of superantigens on the immune system?

Superantigens are a unique class of antigens that can provoke an intense immune response by bypassing traditional antigen-presenting pathways. Their primary effect on the immune system is to cause excessive immune activation. This occurs because superantigens can bind directly to MHC (Major Histocompatibility Complex) molecules and T-cell receptors, leading to the activation of a large number of T cells – often 5-20% of the total T cell population, as opposed to the usual response, which involves a much smaller subset.

This massive activation can lead to a hyper-inflammatory response, characterized by the excessive release of cytokines, which can result in conditions such as toxic shock syndrome. This excessive immune response can be damaging to the host and can overwhelm regulatory mechanisms designed to control immune activity.

While superantigens do not directly eliminate bacterial cells, their ability to induce a strong immune response means they can ultimately contribute to the eradication of infections, but their primary role is not the direct killing of pathogens. Promoting antibody production is one result of immune activation, but it is not the primary effect attributed to superantigens. Similarly, they do not typically suppress the immune response; rather, their hallmark is the stimulation of an overwhelming immune reaction.