Which cell is the primary professional antigen-presenting cell that primes naive T cells?

Which cell is the primary professional antigen-presenting cell that primes naive T cells?

• A. B cells
• B. Macrophages
• C. T cells
• D. Dendritic cells

Answer: (D)

Dendritic cells are the most potent professional antigen-presenting cells for priming naive T cells. They capture antigen in peripheral tissues and migrate to draining lymph nodes, where they present peptides on MHC molecules to naive T cells and provide strong costimulatory signals (like CD80/86 and CD40) that are essential for full T cell activation. They also release cytokines that shape T cell differentiation. B cells and macrophages can present antigen, but they’re less effective at initiating responses from naive T cells; B cells mainly present to already-activated or memory T cells and depend on antigen-specific B cell receptor–mediated uptake, while macrophages function best as APCs during ongoing immune responses rather than at the initial priming. The dendritic cell’s combination of high MHC and costimulation, plus its ability to migrate to lymph nodes to encounter naive T cells, makes it the primary cell responsible for priming naive T cells.

Dendritic cells are the most potent professional antigen-presenting cells for priming naive T cells. They capture antigen in peripheral tissues and migrate to draining lymph nodes, where they present peptides on MHC molecules to naive T cells and provide strong costimulatory signals (like CD80/86 and CD40) that are essential for full T cell activation. They also release cytokines that shape T cell differentiation. B cells and macrophages can present antigen, but they’re less effective at initiating responses from naive T cells; B cells mainly present to already-activated or memory T cells and depend on antigen-specific B cell receptor–mediated uptake, while macrophages function best as APCs during ongoing immune responses rather than at the initial priming. The dendritic cell’s combination of high MHC and costimulation, plus its ability to migrate to lymph nodes to encounter naive T cells, makes it the primary cell responsible for priming naive T cells.