IMM: BLOCK 2: EXAM 2 REVIEW QUIZ

T Cell Receptor (TCR)

• The alpha TCR gene is located on chromosome 14.
• The beta TCR gene is located on chromosome 7.
• The delta TCR gene is located on chromosome 14.
• The gamma TCR gene is located on chromosome 7.

T Cell Development

• There are two distinct lineages of T cells based on their expression of TCR chains.
  • Alpha:beta T-cell receptors
  • Gamma:delta T-cell receptors
• Both alpha:beta and gamma:delta T cells are lost in a deficiency of the signaling receptor Notch1.
• T cell progenitors develop within the thymus.
• T cell progenitors originate in the bone marrow.

T Cell Activation

• T-cells recognize antigens presented by MHC molecules.
• The binding of pMHC:TCR and CD4, followed by the co-stimulatory binding of CD28:CD8-/86 (B7), produces T cell activation.
• T-cells require two signals for activation.
  • TCR with p:MHC
  • Co-stimulatory signal with B7 (CD80/86) with CD28

Pre-TCR Complex

• The pre-TCR complex consists of the beta-chain of TCR and CD3 molecules.
• The pre-TCR complex functions in:
  • Signaling productive rearrangement of TCR beta for further proliferation
  • Suppressing further rearrangement of the beta-chain
  • Preparing cells for rearrangement of the alpha-chain

T Cell Selection

• Positive selection commits T-cells to either CD4 or CD8 single-positive T-cells.

Professional Antigen-Presenting Cells (APCs)

• The three phagocytes are: macrophages, neutrophils, and dendritic cells.
• The three professional APCs are: dendritic cells, macrophages, and B-cells.

Thymus

• Immature thymocytes travel from the cortex to the medulla during development.
• The thymus contains a network of epithelial cells for structure.
• The thymus is associated with positive and negative selection.
• The thymus is the site of T-cell development.

T Cell Differentiation

• T-cells commit to the single-positive cell type of either CD4+ or CD8+ during positive selection.
• All T-cells express CD3.

Other Immune Cells

• NK cells have KIRs and KARs.
• NKT cells only have TCRs.

T Cell Signaling

• ZAP70 is the tyrosine kinase that transmits the signal onward along the T-cell signaling pathway when activated.
• ZAP70 transmits the signal for T-cell development and activation.

TCR Rearrangement

• Successive rearrangements can rescue an initial nonproductive beta-chain rearrangement.
• Rescue is possible only if that rearrangement involves D and J segments associated with the C-beta-2 gene segment.

This quiz covers the structure and function of T Cell Receptors (TCR), detailing the genetics involved and the development and activation of T cells. Key topics include TCR gene location, T cell lineages, and the mechanisms of T cell activation through MHC molecules. Test your understanding of T cell biology and its importance in the immune response.