All of the following are Antigen Presenting Cells (APC), except:
## Core Concept
Antigen-presenting cells (APCs) are crucial components of the immune system. They process and present antigens to T-cells, activating an immune response. Key APCs include dendritic cells, macrophages, and B lymphocytes.
## Why the Correct Answer is Right
The correct answer, , is not typically classified as an antigen-presenting cell. While it plays a role in the immune response, its primary function is not antigen presentation.
## Why Each Wrong Option is Incorrect
* **Option A:** Dendritic cells are professional APCs and play a critical role in initiating the immune response by presenting antigens to T-cells.
* **Option B:** Macrophages are also professional APCs that engulf and digest cellular debris and pathogens, then present antigens on their surface.
* **Option C:** B lymphocytes can act as APCs, especially when they recognize antigens via their surface-bound antibodies.
## Clinical Pearl / High-Yield Fact
A key point to remember is that not all cells can act as APCs; the ability to process and present antigens efficiently is limited to certain cell types.
## Correct Answer: .