Toll-like receptors (TLRs) permit certain cells of the innate immune system (such as macrophages and dendritic cells) to recognize certain molecules that are unique to microorganisms, such as bacteria, viruses, and fungi. This recognition triggers a signaling pathway that leads to the activation of the immune response. TLRs are not found on the surface of cytotoxic T cells, helper T cells, or antigen-presenting cells.

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Toll-Like Receptors

Question 5

Multiple Choice

Toll-like receptors:

A) permit certain innate immune system cells to recognize certain molecules that are unique to microorganisms.
B) are found on the surface of cytotoxic T cells, and are used to recognize infected cells.
C) present foreign antigens on the surface of macrophages and dendritic cells.
D) are found on the surface of helper T cells, where they recognize antigens presented by antigen presenting cells.
E) are used by macrophages and dendritic cells to signal helper T cells that an infection is under way.

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