Which of the following statements best describes the "two-signal requirement" for naive lymphocyte activation?
A)Lymphocytes must recognize two different antigens to become activated.
B)Lymphocytes must recognize the same antigen at two sequential times to become activated.
C)Lymphocytes must recognize antigen and respond to another signal generated by microbial infection to become activated.
D)Both naive B and naive T lymphocytes must simultaneously recognize antigen for either to be activateD.
E)When lymphocytes recognize antigen,the antigen receptors must activate two-signal transduction pathways to become activated.

Question

Quizplus · Accepted Answer

Naive lymphocytes will not become activated by antigen alone (signal 1).In addition,they require "costimulatory" signals (signal 2),which are either microbial products or molecules on host cells induced by microbial infection.The molecules that provide signal 2 bind to receptors on the lymphocytes that are distinct from the clonally distributed antigen receptors.Each lymphocyte cannot generally recognize more than one antigen.Although lymphocyte activation may require recognition of antigen molecules by more than one antigen receptor,the two-signal requirement does not refer to this.There is no general requirement for both T and B cells to recognize the same antigen for activation of either to occur.The two-signal requirement does not refer to antigen receptor-associated signal transduction pathways.

Which of the Following Statements Best Describes the "Two-Signal Requirement