Toll-like receptors (TLRs) are described as which of the following?

• A. They protect adult flies from infection
• B. They enhance phagocytosis
• C. They are found on all host cells
• D. They only play a role in adaptive immunity

Answer: (B)

Toll-like receptors are pattern recognition receptors of the innate immune system. They detect conserved microbial components and trigger signaling that activates innate immune cells such as macrophages and dendritic cells. This signaling ramps up the cells’ ability to engulf and destroy pathogens (phagocytosis) and to release inflammatory cytokines that coordinate the immune response. So, describing TLRs as enhancing phagocytosis captures how recognition of microbes translates into stronger phagocytic activity and inflammatory signaling. They aren’t found on every cell type and they function primarily in innate immunity, with a role in shaping adaptive responses. The historical link to Toll in Drosophila is interesting but does not define their function in humans.