Final answer:
Macrophages recognize pathogens using pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and activate the expression of cytokines and co-stimulatory molecules crucial to adaptive immunity. The option (D) is correct.
Step-by-step explanation:
Macrophages recognize pathogens by using pattern recognition receptors (PRRs), which are molecules on macrophages and dendritic cells that recognize molecular signatures of pathogens.
Toll-like receptors (TLRs) are a type of PRR that recognizes molecules shared by pathogens but distinguishable from host molecules. When macrophages recognize pathogens, they activate the expression of cytokines and co-stimulatory molecules crucial to adaptive immunity. Therefore, option (D) is correct.
This question is not complete, Here I am attaching the complete question:
The response of macrophages to pathogenic stimuli is an important first step in innate immunity and plays an important part in the ultimate success or failure of an organism's attempt to resist pathogenic infection. Macrophages recognize pathogens by a diverse family of pattern recognition receptors. What activates the expression by macrophages of a variety of cytokines and co-stimulatory molecules crucial to adaptive immunity?
(A) CXCR4
(B) Mac-1
(C) SDF-1
(D) TLR-4
(E) IL-8