Immune System

Where are hematopoietic stem cells found?

Bone marrow

T/F? Humans can be infected with SIV and cause disease

False

T/F? PMBCs are a good in vivo model for studying HIV

False- In vivo means animal studies

What are macrophages produced by?

Myeloid stem cells (in bone marrow)

What is RNA-DNA

Reverse transcription

What is mRNA-polypeptide

Translation

Inflammation

-Helps promote antibody and WBC transfer from blood to site of infection -Results in vasodilation of the area of the infection, resulting in more blood to that area -Allows plasma to escape to surrounding tissues

Describe the Adaptive Immunity Humoral response

1. After a naive B cell encounters a FREE PATHOGEN and binds an antigen with its BCR. 2. The TH2 subset of helper cells releases CYTOKINES, triggering the B cell to begin PROLIFERATING and then developing into two populations of cells, MEMORY B CELLS for responses to subsequent infections and PLASMA CELLS which secrete ANTIBODIES that can bind specific antigens on EXTRACELLULAR pathogens

Describe Lymph node structure and how it relates to Immune response

1. As lymph percolates through a node, any particulate antigen will be trapped by the cellular network of phagocytic cells and dendritic cells. 2. The overall architecture of the lymph node provides an ideal micro-environment for lymphocytes to effectively encounter and respond to trapped antigens 3. The lymph node contains 3 regions, CORTEX, PARACORTEX AND MEDULLA 4. As an antigen is carried into the node via lymph, it is frequently trapped, processed and presented together with class II MHC molecules by the DENDRITIC CELLS 5. This occurs in the paracortex, resulting in TH CELL activation 6. Initial activation of other lymphocytes also occurs in the paracortex. Once activated, TH cells and B CELLS migrate to the cortex and enter a structure called a primary follicle. 7. Here, cellular interactions between dendritic cells, B cells, and TH cells take place leading to the development of a secondary follicle with a central GERMINAL CENTER 8. Within this structure memory B cells and plasma cells are formed. The memory cells remain in the germinal center but the PLASMA cells leave the germinal center and go to the medulla where they secrete antibodies

Describe cell mediated response

1. Cells infected with a pathogen can display ANTIGENS. This helps identify infected cells from healthy cells, marking them for destruction. 2. The immune cell involved in this destruction is the CD8+ T CELL 3. This process is initiated when the immune cell binds the pathogen fragment on the infected cell with its TCR 4. The immune cell also binds the infected cells MHC-I (found on almost all nucleated body cells) with its CD8 PROTEIN 5. Complete activation of the immune cells requires cytokines from the TH1 subset of helper cells 6. The immune cell them proliferates and differentiates into effector cells called CYTOTOXIC T LYMPHOCYTES (CTL) and memory cells 7. The effector cells release compounds with CYTOTOXIC ACTIVITY such as PERFORIN that pierces the membrane of the infected cell, triggering APOPTOSIS

Describe leukocytes from phagocytosis to post phagocytosis

1. Following VASODIALATION, leukocytes, including phagocytic cells, are able to migrate to the infection site 2. Directed by CYTOKINES, phagocytic cells migrate toward the PATHOGEN and engulf it. 3. In the phagocytic cell, the microbe is contained within a PHAGOSOME which fuses with a LYSOSOME, forming a PHAGOLYSOSOME, which contains digestive enzymes and a low pH that destroy the microbe 4. if the phagocytic cell is specialized to activate the acquired immune response, it will retain microbial ANTIGENS with its MHC-II PROTEIN located on its cells surface. 5. These cells are known as ANTIGEN PRESENTING CELLS (APCs) 6. After phagocytizing pathogens, the cell is activated, expresses B7 PROTEIN and leaves the site of infection and migrates to nearby LYMPTH TISSUE.

Describe what happens at the infection site

1. Following infection by a pathogen, cells near the site release CYTOKINES, triggering localized INFLAMMATORY RESPONSE. 2. The walls of the blood vessel near the site also relax, resulting in VASODIALATION, which leads to characteristic REDNESS AND SWELLING 3. This also helps PHAGOCYTES leave the blood vessel. 4. They migrate toward replicating pathogens by following the INCREASED CONCENTRATION of the signal molecules

Describe the activation of a naive CD4+T cell

1. Presentation of an ANTIGEN by an ANTIGEN PRESENTING CELL 2. The naive CD4+ t cell must match its TCR to the antigen displayed in MHC-II protein 3. The naive CD4+ t cell must contact that protein displaying the antigen with its CD4 PROTEIN 4. Finally, activated APCs display B7 PROTEINS, which interact with the naive CD4+ T cells CD28 PROTEIN 5. This triggers the now-activated CD4+ T cell to begin producing IL-2 AND Il-2 RECEPTORS 6. The production of these molecules stimulated the CD4+ T cell to begin CLONAL PROLIFERATION, making a population of cells all with the same antigen receptor. 7. This population then differentiates into Th CELLS which release cytokines to activate the immune system and MEMORY CD4+ T CELLS, which fight subsequent infections

Describe CD4+ T cell activation

A Naive CD4+T cell activation first involves an interaction of the lymphocyte with an ANTIGEN PRESENTING CELL, such as a dendritic cell or macrophage The TCr of the naive CD4+T cell must match the ANTIGEN displayed by the DC or macrophage The CD4 protein interacts with the MHCII Finally, the naive CD4+ T cell begins producing the cytokine B7, which binds the IL-2 that the cell also produces The stimulation triggers CLONAL PROLIFERATION, making a population of cells that differentiates into memory T cells and Th cells which release cytokines into the immune system

What kind of cells phagocytize foreign matter to display antigens on its surface?

APCs- like dendritic cells and macrophages

What does transcription result in?

An RNA copy being made from DNA

Does HIV trigger apoptosis or necrosis?

Both

What does a effector CD8+ T lymphocyte destroy?

Cancer cells, foreign graft tissue, and human cells infected with viruses

Describe activation of antigens to t-helper cells

Exogenous ANTIGENS that are OUTSIDE cells, are ingested and processed by the ANTIGEN-PRESENTING CELL and presented with MHC-II to the NAIVE CD4+ T CELL, beginning the process of activation. Once activated the T-Helper cell begins to produce CYTOKINES that help other cells of the immune system perform their functions.

What kind of immune response is inflammation and non-specific cell response?

Innate

What kind of enzyme destroys pathogens during phagocytosis?

Lysozyme

What is the most abundant type of WBC?

Neutrophils

How does the body react to different antigens?

Producing antibodies

What is translation?

The process in which mRNA directs protein synthesis

Where do naive CD8+ cells develop?

Thymus

What is DNA-RNA

Transcription

T/F? A B cell receptor binds the specific antigen only if the shape of the antigen matches the shape of the tip of the receptor.

True

T/F? A modified HIV virus has successfully been used to infect pig-tailed macaques, which are useful animal models.

True

T/F? Antibodies are the secreted form of the B cell receptor

True

T/F? Antibodies can disrupt pathogens membranes

True

T/F? Antibodies opsonize pathogens, to mark them for destruction

True

T/F? Antigen-presenting cells process foreign antigens and present them to CD4+ lymphocytes

True

T/F? Antigens are molecules that can act as identifying characteristics of the cell

True

T/F? Baboons can exhibit AIDs like conditions from HIV-1

True

T/F? CD4+ T cells, following activation, proliferation, develop into effector cells that are either Th1, Th2, or TDTH cells.

True

T/F? CD8+ T cells must be activated by cytokines released by Th1 lymphoctyes

True

T/F? CTls are effector CD8+ T cells that trigger apoptosis in infected and transformed cells.

True

T/F? Individuals with SCID have been a model for HIV disease progression

True

T/F? Infants with higher concentrations of SLPI correlate with lover HIV transmission

True

T/F? Lymph is filtered blood and contains antigens

True

T/F? Lysozyme is found in tears, saliva and other secretions

True

T/F? Macrophages can act as APCs

True

T/F? Necrosis triggers inflammatory response?

True

T/F? PMBCs are useful to monitor infections outside the body because the cells are able to be infected with HIV

True

T/F? Phagocytic cells do not function as well in HIV infected persons because of the loss of Th cells

True

T/F? SLPI has been shown to block HIV infections of cells in vitro

True

T/F? Skin is an effective barrier to HIV

True

T/F? Some cells derived from the myeloid lineage are able to phagocytize pathogens

True

T/F? The cell membrane and cytoplasm contain anitgens

True

Can Chimpanzees be infected with HIV?

Yes, but they generally do not develop AIDS

Trace the development of a naive CD4+ T cell

it begins with lymphoid stem cell forming a T cell in bone marrow, then migration of the T cell to the thymus to develop into a naive CD4+ T cell, then migration of the naive cell to lymph tissue where it encounters an activated APC bearing an antigen, it responds to via its TCr