• Preliminary diagnosis: AIDS, with toxoplasmosis or

  CNS lymphoma

• FInal Diagnosis: cerebral toxoplasmosis, due to AIDS

What are 3 types of Antigen binding molecules?

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1. antibody
2. TCR 
3. MHS class I or II

What do the following antigen binding molecules bind to:

1. antibody
2. TCR
3. MHC Class I or II

1. antibody = binds to large and small molecules
2. TCR = olgopeptides and MHC molecules
3. MHC Class I or II = oligopeptides

true or false

"T-cells see peptides displayed by MHC molecules?"

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How do peptides binds to MHC molecules?

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true or false?

"The t-cell receptor can only see the peptide, not the MHC molecule?"

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false

The T-cell receptor can see both the peptide and MHC molecule

What kind of antigens do the lymph nodes and spleen collect?

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• lymph nodes collect antigens from the epithelium and connective tissue
• the spleen uses antigen-presenting cells (APCs) to capture blood-borne antigens

Where are most dendritic cells (DCs) found, and what are they usually called in these areas?

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What are the best antigen-presenting cells?

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What is the principal function of dendritic cells as an APC?

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What is the principal function of Macrophages as an APC?

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What is the principal function of B lymphocytes as an APC?

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What does histocompatibility mean?

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What is a MHC?

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stands for major histocompatibility complex

Is a cluster of closely linked genes on the 6th human chromosome. 

It encodes for proteins

What are the functions of the proteins encoded by MHC?

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• control T-cell mediated immune responses
• determine the fate of transplanted tissues
• the key molecules encoded by the MHC are the Human Leukocyte Antigen (HLA) molecules

What does MHC do with their peptides?

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• MHC's role is to present one or more peptides to the T-cells

True or false?

MHC class 1 and 2 share the same kinds of isotypes and functions?

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false

MHC 1 and 2 molecules come in different isotypes and differ in function

List three types of human MHC class 1 isotypew that are both "highly polymorphic" and "monomorphic"

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1. HLA-A
2. HLA-B
3. HLA-C

List 2 types of "polymorphic" human MHC class 2 isotypes

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1. HLA-DP
2. HLA-DQ

List one type of human MHC class 2 isotype that is both "oligomorphic" and "highly polymorphic"

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What does polymorphic mean?

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Why is it important to identify HLA polymorphisms (aka HLA typing)?

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What does it mean to say that MHC genes are co-dominant? Why is this significant?

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means that both parental alleles of the MHC gene  are expressed.

This is important since it increases the number of different MHC molecules, thus increasing immune diversity. 

true or false

Expression of MHC molecules differs between tissues and cell types?

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true

What are 3 types of APC class 2 MHC-expressing cells?

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1. dendritic cells
2. macrophages
3. B cells

What are the types of APC class 1 MHC-expressing cells?

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What does MHC class 2 bind to on T-helper cells?

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In the class 2 MHC pathway, what does MHC bind to? What are some examples of this?

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• MHC 2 binds to CD4+ on T-helpers. 
• examples are bacteria, fungi, and bacterial toxins

In the class 1 MHC pathway, what does MHC bind to? What are some examples of this?

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• MHC class 1 binds to CD8+ on cytotoxic T-lymphocytes
• Examples are viruses

What are alloantigens?

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What are the effects of CD8+ cytotoxic T-lymphocytes?

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1. How do T-cells know there's a bad guy?
2. How do they respond?

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1. Cd4+ gets signals to become activated.
2. It then produces cytokines and starts dividing into daughter clones. These clones differentiate into helper, killer, and memory T-cells

Name 3 key molecules invovled in T-cell activation?

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What is the role of CD3 in T-cell activation?

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What is the immunological synapse?

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What is the function of the CD3 T-lymphocyte surface molecule?

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1. What is the function of CD4 in T-cell activation?
2. which ligand does it bind with?
3. where is it expressed on?

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1. signal tansduction
2. binds with Class 2 MHC ligand
3. expressed on APC

1. What is the function of CD8 in T-cell activation?
2. which ligand does it bind with?
3. where is it expressed on?

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1. signal transduction
2. binds to MHC class 1
3. expressed on all nucleated cells

1. What is the function of CD28 in T-cell activation?
2. which ligand does it bind with?
3. where is it expressed on?

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1. signal tansduction (co-stimulation)
2. binds with CD80/86 
3. expressed on APCs

1. What is the function of CTLA-4 in T-cell activation?
2. which ligand does it bind with?
3. where is it expressed on?

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1. negative regulation
2. binds to CD 80/86
3. expressed on APCs

What is necessary for the clonal expansion of T-cells to occur?

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1. T-cells up-regulate the expression of CTLA-4
2. Since CTLA-4 has a higher affinity for CD80 and 86, this affinity shuts down the T-cell response

1. What is secreted after T-cell activation receives its second signal from the CD80/86:CD28 interaction?
2. What overall effect do these secretions have on T-cell functions?

1. Once signaling occurs, T-cell starts secreting IL-2 (T-cell growth factor), and expresses IL-2R.
2. These secretions give rise to cell proliferation for either T helper 1 or 2

What 5 steps follow the binding of the APC MHC 2 molecule with the T-cell?

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1. antigen recognition
2. signal transduction
3. cell activation
4. cell division
5. secretion of cytokines

What are the 2 types of t-cell receptors? What are their difference in terms of abundance, diversity, and antigesn

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• alpha-beta TCRs
• abundance = 90-95% of all T-cells
• diversity = diverse repertoire
• antigens = peptide antigens
• y:g TCRs
• abundance = 5-10% of all T-cells
• diversity = limited repertoire
• antigen = non-peptide antigens

What are the principal actions of IL-2?

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What are the principal actions of IL-4?

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What are the principal actions of IL-5?  

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What are the principal actions of interferon Y (IFN-y)?

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What do IL-2 activated T-cells express? What does this cause to secrete?

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1. they express high affinity IL2r (CD25)
2. this causes IL2 to secrete in an autocrine manner

What happens when IL2 binds to its receptor?

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• IFN-y
• IL-2
• TNF

IL-4

IL-5

IL-13

IL-17A

IL-17F

IL-22

What are the host defenses of:

• TH1
• TH2
• TH17

• TH1 = intracellular microbes
• TH2 = helminthic parasites
• TH17 = extracellular bacteria, fungi

• autoimmune diseases
• tissue damage associated with chronic infection

• cellular immunity
• CD8+ T cells and macrophages

• humoral immunity 
• B cells

• cytokine release
• macrophage activation 
• killing of ingested microbe

• cytokine release
• inflammation
• killing of microbes

true or false

"T cells talk to phagocytes which kill microbes"

What kind of cytokines does TH1 cell release?

What effect does this have on a CD8+ T-cell

• Interferon gamma (IFN-y), TNF, and IL-2
• causes the CD8+ T-cell to undergo clonal expansion and differentiation 

1. List 2 types of cell killing that Cytotoxic T-Lymphocytes (CTLs) and NK Cells perform?
2. What type of killing is finally performed?

1. Perforin/granzyme-mediated cell killing
2. Fas/FasL-mediated cell killing

Both types lead to apoptosis of the target cell

• humoral immunity
• anti-parasite immunity

1. isotype switching
2. affinity maturation
3. plasma cell and B-memory cell generation

1. What are TREGs?
2. What do they do?

1. they are Regulatory T-cells
2. they prevent the actions of autoreactive (anti-self or autoimmune) T-cells

What are the functions of TH17 cells? (list 3)

What types of cytokines do they release?

1. Inflammation, neutrophil response
2. Antimicrobial peptides
3. Increased barrier function

They release IL-17A/F and IL-22