Immuno Ch7

Which of the following statements is TRUE of CD4?

• CD4 is essentially an intracellular glycoprotein

• CD4 is heterodimeric

• CD4 binds processed peptide in its outer groove

• CD4 binds to MHC class II on antigen-presenting cells

What is the T-cell ligand binding B7 on a professional antigen-presenting cell?

• CD28

• CD2

• ICAM-1

• VCAM-1

Which of the following statements is TRUE of Sos (Son of sevenless)?

• Sos itself directly activates Raf

• Sos is recruited to non-phosphorylated LAT

• Sos is a guanine nucleotide exchange factor

• Sos is a GTPase-activating protein

Protein tyrosine kinase activity following T-cell stimulation:

• Phosphorylates and thereby activates phospholipase Cγ1

• Is an inherent property of the T-cell receptor α and β chains

• Is an inherent property of CD3

• Is decreased

The early increase in phospholipase Cγ1 activity following T-cell stimulation:

• Represents a sensitive regulatory negative feedback control mechanism

• Dephosphorylates protein tyrosine kinase inhibitors

• Accelerates hydrolysis of diacylglycerol

• Accelerates hydrolysis of phosphatidylinositol diphosphate

The nuclear AP-1 site responsible for 90% of IL-2 enhancer activity binds:

• The Oct-1 transcriptional factor

•  The Fos/Jun transcription factors

• The nuclear factor of activated T-cells (NFAT)

• The NFκB transcriptional factor

Cross-linking of B-cell surface receptors:

• Is a characteristic feature of thymus-dependent antigens

• Lowers the intracellular Ca²⁺ concentration

• Rapidly phosphorylates the Ig-α and Ig-β chains of the surface Ig receptor

• Requires contiguity of two B-cell epitopes of different specificity on the same antigen molecule