Which of the following is not true regarding super-antigens-
**Super-antigens Core Concept**
Super-antigens are a class of antigens that can cause excessive activation of the immune system by binding to major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) and T-cell receptors (TCRs) on T-cells simultaneously. This leads to a massive release of pro-inflammatory cytokines and a strong T-cell response.
**Why the Correct Answer is Right**
Super-antigens can cause a wide range of clinical manifestations, including fever, rash, and multi-organ failure, due to their ability to activate a large number of T-cells. The mechanism of super-antigen action involves the binding to MHC class II molecules and TCRs, which leads to the activation of T-cells and the release of cytokines. This is in contrast to traditional antigens, which require processing and presentation by APCs before they can activate T-cells.
**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true, as super-antigens can cause a strong T-cell response and activate a large number of T-cells.
**Option B:** This statement is true, as super-antigens can cause a range of clinical manifestations, including fever, rash, and multi-organ failure.
**Option D:** This statement is true, as super-antigens can cause a massive release of pro-inflammatory cytokines and activate a large number of T-cells.
**Clinical Pearl / High-Yield Fact**
Super-antigens are often produced by bacteria, such as Staphylococcus aureus and Streptococcus pyogenes, and can cause a range of clinical manifestations, including toxic shock syndrome and staphylococcal scalded skin syndrome.
**Correct Answer: D. All of the above statements are true regarding super-antigens.**