Antigen presentation

My name is _____ and I’m a 3-year old boy. I came into the ER with yet

another bacterial infection.

History: I have a history of repeated bacterial and viral infections. Passive

immunization with antibodies was always successful, but active immunization

with non-virulent bacteria always failed.

Physical examination: I’m short for my age.

Tests: My complete blood count was normal. More specific assays were

done, for example, my leukocyte ability to phagocytose bacteria was normal,

and the phagocytosed bacteria were digested normally.

What would you consider might be the cause of my condition?

1. Inactive cytotoxic CD8+ T cells

2. Inability to make antibodies

3. Inability to destroy antibody-coated bacteria

4. Incomplete major histocompatibility molecules (MHC)

Adaptive (acquired) immunity

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Ag

WHITEBOARD

MHC expression is dynamic

My name is _____ and I’m a 3-year old boy. I came into the ER with yet

another bacterial infection.

History: I have a history of repeated bacterial and viral infections. Passive

immunization with antibodies was always successful, but active immunization

with non-virulent bacteria always failed.

Physical examination: I’m short for my age.

Tests: My complete blood count was normal. More specific assays were

done, for example, my leukocyte ability to phagocytose bacteria was normal,

and the phagocytosed bacteria were digested normally.

What would you consider might be the cause of my condition?

1. Inactive cytotoxic CD8+ T cells

2. Inability to make antibodies

3. Inability to destroy antibody-coated bacteria

4. Incomplete major histocompatibility molecules (MHC)

Bare lymphocyte syndrome (BLS)

Rare genetic disorder.

Leukocyte cells develop normally, but lymphocyte activity lacks.

This syndrome stems from inexpression of MHC class II, caused by the absence of one of several transcription factors required for expression of MHC class II.

These proteins include:Class II trans-activator (CIITA) Regulatory factor of the X box 5 (RFX5) RFX-associated protein (RFXAP) RFX ankyrin repeats (RFXANK; also known as RFXB)

1. Inactive cytotoxic CD8+ T cells

2. Inability to make antibodies

3. Inability to destroy antibody-coated bacteria

4. Incomplete major histocompatibility molecules (MHC)

What would you consider might be the cause of my condition?

1. Inactive cytotoxic CD8+ T cells

2. Inability to make antibodies

3. Inability to destroy antibody-coated bacteria

4. Incomplete major histocompatibility molecules (MHC)

My name is _____ and I was infected intranasally with flu

virus. The virus attacked my nasal epithelial cells. Now,

my sensitized cytotoxic CD8 lymphocytes aim to kill

these virus-infected nasal epithelial cells. Their

receptors recognize foreign proteins on the epithelial

surface in association with:

A. MHC class I heavy chain only B. MHC class I heavy chain and 2-microgIobulin C. MHC class I heavy chain and lgG D. MHC class II alpha-chain and beta-chain E. MHC class II alpha-chain only

My name is ______ and I joined a clinical trial in which I

received a substance that prevented the acidification of

lysosomes within my antigen-presenting cells. As a

result, my affected cells showed impaired interaction with

lymphocytes upon antigen exposure.

The observed effect most likely results from a low cell

surface expression of which of the following molecules?

A. MHC Class I B. MHC Class II C. T-cell receptor D. Cytokine receptors

Homework:

List the important HLAs in human autoimmune diseases

For example HLA-DQ2 => Celiac