The strength of integrin-dependent binding of T cells to antigen-presenting cells (APCs)may be rapidly increased by which one of the following mechanisms?
A)Integrin clustering and increased integrin affinity are induced by chemokines and antigen recognition.
B)Integrins stored in cytoplasmic organelles are mobilized to the T cell surface in response to TCR-mediated signals.
C)Integrin gene transcription is enhanced by chemokine-generated signals.
D)The affinity of integrin ligands on APCs is increased in response to chemokines.
E)Integrin ligands stored in cytoplasmic granules in the APCs are mobilized to the cell surface in response to CD40-CD40 ligand interaction.

Question

Quizplus · Accepted Answer

T cell integrin affinity is enhanced by "inside-out signaling" in response to antigen binding to the T cell receptor (TCR)and chemokine binding to chemokine receptors.In addition,antigen and chemokines can induce clustering of integrins in the region of the T cell membrane in contact with the antigen-presenting cell (APC).These changes cause stronger T cell binding to APCs displaying the peptide-MHC complex that the T cell recognizes,thus ensuring prolonged T cell/APC contact and T cell activation.Integrins are not stored in cytoplasmic granules,and transcriptional activity cannot account for rapid changes in integrin-mediated binding.Integrin ligands (such as ICAM-1)do not undergo changes in affinity,nor are they stored in cytoplasmic granules.

The Strength of Integrin-Dependent Binding of T Cells to Antigen-Presenting