Antigen Capture & Presentation Flashcards
These antigen presenting molecules are on all nucleated cells.
MHC I
***Also called HLA
These antigen presenting molecules are on professional APCs (DCs, macrophages, B-cells).
MHC II
T-lymphocytes DO NOT recognize antigens in free or soluble forms. They recognize portions of _______ antigens associated with HLA (MHC).
Protein
The total set of MHC/HLA alleles are present on each chromosome. The set of alleles on each chromosome is called an MHC/HLA _________. Encode protein antigens central for immune system to discriminate between self and non-self.
Haplotype
Most humans are heterozygous and have two MHC/HLA haplotypes, one from Mom and one from Dad. Both are expressed simultaneously exhibiting ________ (generates more diversity this way).
Co-dominance
This class of MHC/HLA gene is encoded by three separate gene regions in the locus (HLA-A, HLA-B, HLA-C). They are membrane bound glycoproteins and are expressed on all nucleated cells.
MHC I
What type of T-cells do MHC I bind to?
CD8+ cytotoxic T-lymphcytes (CTLs)
What does MHC I inhibit?
NK cells
(MHC I) Alpha-chain translated into _____ as glycoprotein. Alpha-chain interacts with Beta2 microglobulin. Complex transported to cell surface.
ER
What region are class II MHC/HLA encoded by?
HLA-D (HLA-DP; HLA-DQ; HLA-DR)
What type of T-cells do MHC II bind to?
CD4+ T-lymphocyte
T/F. Only one peptide binds to a molecule of MHC/HLA at any one time, but the same molecule of MHC/HLA has the capacity to bind to multiple peptides.
True
There are _______ in the floors of the peptide-binding clefts that the side chains of the amino acids on the antigen peptides fit into and anchor the peptides in the cleft.
Pockets
These are antigens coded on Y chromosome. They’re associated with acute rejection of male grafts in female recipients.
H-Y
Microbes that enter the body are either:
– Phagocytosed or pinocytosed by APCs in the tissues
– (Enter via the periphery) They are filtered by the lymph and lymphoid tissues
– (In the blood) Filtered by the ________
Spleen
This type of APC can activate naive mature T cells and are in tissues or blood.
DCs
Classical DCs are in all tissues, but __________ DCs are in the blood and tissues. These promote innate anti-viral state.
Plasmacytoid DCs (pDC)
Which class of MHC work against intracellular pathogens and self?
MHC I
What class of MHC work against extracellular pathogens?
MHC II
T/F. Even in the absence of infection, protein degradation and peptide transport occur simultaneously. MHC/HLAs carry peptides derived from normal self-proteins, but normally these do not provoke immune responses.
True
***MHC I carry self proteins
During this, DCs can ingest virally infected or transformed cells and display Ag to CTLs via MHC I.
Cross-Presentation
***Remember, MHC I is usually intracellular. DCs ingested virus from extracellular environment, and displayed to MHC I.
A large number of autoimmune diseases and susceptibility to infectious agents are associated with particular ______ alleles.
HLA
This HLA-associated disease exhibits inflammation of the spine, and is due to the expression of the HLA-B27 allele. This allele can not bind a critical antigenic peptide, allowing it to cause disease.
Ankylosing spondylitis
This HLA-associated disease occurs as a result of Streptococcus pyogenes infection. There is a generation of Abs against the streptococci that cross react with cardiac tissue.
Rheumatic fever
Patients who have the _______ allele are more prone to develop Rheumatic fever.
HLA-DR4
This HLA-associated disease results in a defect in salivation and lacrimation. Associated with HLA-DR3.
Sjogren’s Syndrome
This disease is associated with HLA-DQw8 and others.
Insulin-dependent diabetes mellitus
This disease is associated with HLA-B3.
Psoriasis
Class I Antigen-processing defects in renal cell carcinoma are due to a down-regulation of ______.
TAP
***Brings peptide (antigen) from cytosol into ER and makes MHC/Antigen complex
In this rare disease, the TAP protein is nonfunctional, so no peptides can enter the ER. Since Class I molecules cannot leave the ER unless they have bound a peptide, cells cannot present antigens on their cell surface. Symptoms include chronic respiratory infections, and poor response to viruses.
Bare Lymphocyte Syndrome (Class I)
This disease can be caused by an inherited defect in CIITA, leading to a deficiency in HLA class II expression on cells and non-functioning T-lymphocytes. HLA II genes are turned on by transcriptional activator CIITA, so without it HLA is not expressed. Patients have severe chronic infections.
Bare Lymphocyte Syndrome (Class II)
What polypeptide chains make up MHC I?
Alpha
Beta2-Microglobulin
What polypeptide chains make up MHC II?
Alpha
Beta
What is the binding site on MHC I for T-cells?
Alpha-3 region binds CD8
What is the binding site on MHC II for T-cells?
Beta-2 region binds CD4
This inhibitor is on the surface of all cells, and protects against complement.
DAF
