Which of the following allows a limited range of immune cells to detect and respond rapidly to a wide range of pathogens that share common structures?
A. Pattern recognition receptors (PRRs)
B. Cytokines
C. Chemokines
D. T cells .
Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens.
PRRs play a crucial role in the proper function of the innate immune system and are germline-encoded host sensors, which detect molecules typical for the pathogens.
Choice B is incorrect because cytokines are not receptors but rather signaling molecules that regulate immunity.
Choice C is incorrect because chemokines are not receptors but rather signaling molecules that attract immune cells to sites of infection.
Choice D is incorrect because T cells are not receptors but rather white blood cells that assist B cells or directly kill infected cells.
Therefore, the Correct Answer is A.