Lecture 6- T Cell Receptors & MHC Molecules Flashcards
Which immune cell recognition can:
- Directly recognize and bind antigens
- Recognize diverse antigens
- Proteins, carbohydrates, lipids, nucleic acids
B cell recognition (BCR & antibody)
Which immune cell recognition can:
- ONLY recognize antigens when presented by MHC molecules
- recognize only peptide antigens (protein)
T cell recognition (TCR)
What are accessory molecules?
Molecules (integral membrane proteins) that are necessary or merely augment the T-cell response to an antigen.
(they assist by enhancing cell-cell adhesion, transducing signals, and promoting activation.)
What are the 2 domains of the segment protruding from the membrane?
- C domain: close to the membrane
- V domain: distant from the membrane
What are the TCR accessory molecules?
- CD4 (Helper T)
- CD8 (Cytotoxic T)
- CD3 complex
- Zeta-zeta dimer (greek)
- LFA-1 (CD11)
(come back to slide 8 and make cards for individual molecules)
What are ITAMs?
Immunoreceptor tyrosine-based activating motifs
- activated by phosphorylation
- BCR and TCR accessory proteins, as well as other receptor proteins
- essential for signal transduction
ydelta T cells:
- mysterious
- Derived from a separate cell lineage
- (may be) first-line defense at epithelial tissues
- NOT MCH restricted
- (may) recognize carbohydrate antigens presented by a CD1 molecules (similar to MHC)
Does TCR perform class switching (replacement of heavy chain)?
No
Does a TCR perform somatic hypermutation/ affinity maturation?
No
What factors contribute to TCR diversity?
- Gene rearrangements
- Multiple V region genes
- random combinations of chains
- 1016-1018 variations
What is MCH?
Major histocompatibility complex
- Area of the genome coding for a series of proteins expressed ion the cells in the body
What is HLA (human leukocyte antigens responsible for?
graft rejection, or tissue compatibility
Why do T-cells interact with MCH molecules/proteins?
to determine if the material contacted belongs in the body
- if the material is recognized as harmful, both the material and APC are destroyed
What do MCH molecules do?
They recognize protein antigens and present them to T cells through APCs
( antigens include both self-proteins and foreign proteins produced within the cells [ex: viral proteins that take over the cell’s machinery in order to replicate the virus] )
On what cells is MCH class 1 found?
All nucleated cells
What are some features of MCH 1?
- heterodimer: α and ß chains
- presents peptides of about 8-11 amino acids
- presents endogenous(intracellular) peptides
