Toll-like receptors are receptor proteins on ___________.

• A. Granulocytes that destroy parasitic helminths.
• B. Phagocytes that recognize foreign or microbe-associated molecules.
• C. Viruses entering the body which stimulate the immune system.
• D. Mucus producing cells that trigger mucus production when they bind with an allergen.

Answer: (B)

Verified step by step guidance

1. Understand the role of Toll-like receptors (TLRs) in the immune system. TLRs are a class of proteins that play a key role in the innate immune system by recognizing structurally conserved molecules derived from microbes.
2. Identify the types of cells that typically express Toll-like receptors. TLRs are primarily found on immune cells such as phagocytes, which include macrophages and dendritic cells.
3. Consider the function of phagocytes in the immune response. Phagocytes are responsible for engulfing and digesting cellular debris and pathogens, and they use TLRs to detect the presence of foreign molecules.
4. Evaluate the options given in the problem. The correct context for TLRs involves their presence on phagocytes, which recognize foreign or microbe-associated molecules, rather than granulocytes, viruses, or mucus-producing cells.
5. Conclude that the correct completion of the sentence is: 'Toll-like receptors are receptor proteins on phagocytes that recognize foreign or microbe-associated molecules.'