When T cells are activated by recognizing peptide:MHC complexes on dendritic cells in the lymph node, they up-regulate the receptor CD69. For T cells expressing a given T-cell receptor, the initial strength of the T-cell receptor signal can be modulated by varying the number of peptide:MHC complexes on the dendritic cells, or by varying the affinity with which the T cell-receptor binds to the peptide:MHC complexes. As a result, T cells stimulated with stronger T-cell receptor signals will maintain high expression of CD69 for one or two days longer that if those same T cells were stimulated with weaker T-cell receptor signals. Therefore, T cells stimulated with weaker T-cell receptor signals are likely to:
A) Die by apoptosis
B) Undergo more rounds of proliferation that T cells stimulated with stronger T-cell receptor signals
C) Migrate to the B-cell zones of the lymph node
D) Have reduced effector functions, such as cytokine production
E) Egress from the lymph node 1-2 days earlier than T cells stimulated with stronger T-cell receptor signals

Question

Quizplus · Accepted Answer

T cells stimulated with weaker T-cell receptor signals express CD69 for a shorter duration, which is a marker for recent activation. Since CD69 expression is linked to retention in the lymph node, lower or shorter expression would lead to earlier egress from the lymph node compared to T cells stimulated with stronger signals.

When T Cells Are Activated by Recognizing Peptide:MHC Complexes on Dendritic