Which of the following is not an antigen-presenting cell?

 # Which of the following is not an antigen-presenting cell?

A. B cell

B. Dendritic cell

C. T cell

D. Macrophage

The correct answer is C. T cell.

Explanation:

Professional Antigen-Presenting Cells (APCs) are specialized immune cells that process and display foreign antigens complexed with Major Histocompatibility Complex (MHC) class II molecules on their surfaces. Their primary role is to present these antigens to T cells to trigger an immune response.

The classical professional APCs are:

Dendritic cells: The most potent APCs, crucial for initiating primary immune responses by activating naive T cells.

Macrophages: Phagocytes that engulf pathogens and present antigens to T cells to sustain ongoing immune responses.

B cells: Internalize antigens via their specific surface antibodies and present them to helper T cells to receive the signals necessary for antibody production.

T cells, conversely, are the "responders." They use their T cell receptors (TCRs) to recognize the antigens presented by the APCs. They do not serve the primary function of capturing and presenting antigens.