CD 3 receptor is seen in ?
## **Core Concept**
The CD3 receptor is a crucial component of the T-cell receptor (TCR) complex on the surface of T lymphocytes. It plays a significant role in the signaling process after the TCR engages with an antigen. The TCR complex includes the TCR itself, CD3, CD4 or CD8, and CD45.
## **Why the Correct Answer is Right**
The correct answer, T-helper cells (or more broadly T cells, which include T-helper cells), expresses the CD3 receptor. CD3 is a part of the TCR complex on all T cells, which are essential for the cell's activation upon antigen presentation. The CD3 molecule is critical for signal transduction inside the T cell upon TCR engagement.
## **Why Each Wrong Option is Incorrect**
- **Option A:** B cells primarily express CD19, CD20, and CD21 as their surface markers, not CD3. B cells are another type of lymphocyte crucial for humoral immunity.
- **Option B:** Plasma cells are mature B cells that produce large amounts of antibodies. They do not express CD3; instead, they are characterized by their ability to secrete immunoglobulins.
- **Option D:** Neutrophils are a type of granulocyte and a component of the innate immune system. They do not express CD3; their surface markers include CD neutrophil-specific antigens.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that CD3 is a marker for T cells, and it is used in the diagnosis and monitoring of T-cell disorders. Immunohistochemistry for CD3 is commonly used in pathology to identify T cells in tissue samples.
## **Correct Answer:** . T cells