Chapter 5 Antigen Recognition by T lymphocytes (Exam 2)

T-cell is similar to immunoglobin protein on B lymphocytes (T/F)

True

T-cell Receptor doesn’t remain anchored to the cell membrane, therefore it is released as antibodies (T/F)

False

RAG gene

only used in lymphocytes, and is essential for v(d)j in B/T cells

SCID

No rag=no adaptive immune system (B/T cells)

CD3 proteins are not required to move the T-cell Receptor protein from the ER to the cell surface (T/F)

False

MHC class 1

• Intracellular antigens

• activate CD8 T lymphocytes

• directly attaches to cells & kills (killer T)

• Viral infected/cancerous

• b2-microglobulin

• binds to antigens in cytosol

• induces death viral infected cells

• cytotoxic t cell

MHC class 2

• Extracellular Antigens

• activates CD4 T-cells

• helper & regulator (Helper T)

• releases cytokines (from pathogens and antibodies) inflammatory

• activation of macrophages

• bind to antigens isolated in membrane compartments

polymorphic

binding site is flexible, so promiscuous binding

Antigen Processing

peptide antigens are produced by pathogens and their products are called this

Antigen presentation

MHC molecule peptide presenting antigen to T-cell receptor

peptide must be bound to MHC molecule and displayed on cell surface

T cells that are not exposed to antigens are induced to undergo clonal expansion with differentiations into effector T cells. (T/F)

False

The CD4 and CD8 proteins produced in T lymphocytes are considered as

part of the immunoglobulin family of proteins. (T/F)

True

Intracellular antigens (e.g. from active virus infections)-

-are attached to CD8 TCRs.

Extracellular antigens (e.g. from bacteria living in interstitial

tissue spaces) -

-are attached to CD4 TCRs.

MHC proteins bind both TCR and the co receptor (CD4, CD8)

True

Viruses are the main contributors of antigen molecules processed by MHC class 2 molecules. (T/F)

False

uses multiple enzymes to recognize antigens, tag them with the small protein ubiquitin, and then use that as a signal to degrade the protein in the proteasome, within the cytosol (MHC 1)

ubiquitin proteolytic pathway

MHC Class 1 Antigen processing

• cytosolic antigen is generated by proteolysis through the UPP and the

  proteasome

• The antigen is transported into the ER via TAP

• The peptide-loading complex attaches the peptide antigen to the MHC I protein.

  – This includes calnexin, b2-microglobulin, and

  other proteins.

• Vesicular transport moves the antigen to the cell surface

MHC class II receptors interact with antigens generated from extracellular material isolated by endocytosis. (T/F)

True

MHC Class 2 antigen processing

• The extracellular antigen is generated by proteolysis within an endolysosome

• The antigen is blocked from binding to the MHC II protein by the CLIP peptide (from the invariant chain protein)

• Within the vesicle, the antigen is bound to the MHC II proteins with the assistance of the HLA-DM protein

• Vesicle fusion moves the antigen-MHC II complex to the cell surface.

cross-presentation

Antigens located class 2 pathway of antigen presentation can be transferred to the class 1 antigen presentation

The genes for the MHC proteins are located on this chromosome

Chromosome 6

Immunoglobulin proteins (i.e. antibodies) are also isotypes. (T/F)

True

Antigen binding to a T cell receptor (TCR) is not dependent on both the MHC (HLA) protein isoform, and the antigen itself. (T/F)

False

HLA-DM

protein stablizing peptide binding to MHC 2

IL-7

cyotokine signaling molecule driving pre-b-t cell deveopment

VLA-4 integrin

Present on surface of t lymphocytes that binds to mucosal cam

CCL12 +19

aTTRACT b cell lymphocytes