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 << Who is this?

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)CIITA Regulatory factor of the X box 5 (RFX5)RFX5 RFX-associated protein (RFXAP)RFXAP RFX ankyrin repeats (RFXANK; also known as RFXB)RFXANK 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