Quiz 2 Chapter 15

nucleated

Cells that express MHC class I molecules are all ______ cells

3 alleles from mom and dad

How many MHC alleles do we inherit from our mother? From our father?

One

How many different (unique) antigens would the BCRs on one B cell be able to bind?

One

How many different (unique) antigens would the TCRs on one T cell be able to bind?

Nucleated cell- 6 alleles (only 6 from MHC I) and APCs- 12 alleles (6 for MHC I and 6 for MHC II)

How many peptides can each MHC molecule display at one time?

antigen presenting cells (macrophages, dendritic cells, B cells)

MHC class II molecules are expressed by ________

Figure 15.1

T cells- Dendritic Cells present antigen to T cytotoxic via MHC I and Helper T cells via MHC II. Co stimulatory molecules from dendritic cells activate, along with the presented antigen, the naïve helper T and cytotoxic T cells. 2. B cells- the antigen bound to the BCR, as well as cytokines from Helper T cells confirming the invader. Innate is mainly cytokines

Tolerance

the ability of the adaptive immune system to ignore any given molecule and the decreased reactivity of the immune system to a specific antigen. This allows the immune system to distinguish between normal hosts cells from invading microbes. This is critical because without it, the immune system would turn against the body's own cells, as well as attack harmless substances

8-10, endogenous

The size of the MHC class I epitope is _____ amino acids; source of peptide is ___________

13-25, exogenous

The size of the MHC class II epitope is ________ amino acids; source of peptide is ______

B7 receptor on APC binding to CD28 on mature naive T cell

This is the second signal to activate any type of naive mature T cell

tonsils, spleen, lymph nodes, Peyer's patch, MALT, SALT

What are the secondary lymphoid organs?

dendritic cells, macrophages, B cells

What are the three cells that can act as antigen presenting cells: ________ -> best APC ______ -> good APC ______ -> non-phagocytic APC

Perforin and proteases

What are the two enzymes contained in a Tc death package?

The effector T cell recognizes the invading microbe peptides presented on the MHC class I molecules

What does an effector T cytotoxic cell recognize in order to kill an infected cell?

MHC 1 + peptide

What does the TCR bind to on the APC?

MHC class II + peptide

What does the TCR bind to on the APC?

CD4 stabilizes the MHC class II and TCR binding of a helper T cell

What does the co-receptor bind to?

It stabilizes the binding of the TCR to MHC I

What does the co-receptor bind to?

Human leukocyte antigens (HLA)

What is another name for MHC molecules in humans?- Human MHC molecules (markers for tissue compatibility)

CD4

What is the co-receptor on this cell?

CD8

What is the co-receptor on this cell?

B7 (on the nucleated cell/ APC) to CD28

What is the second signal to activate this type of naive mature T cell?

A degraded portion of the measles viral peptides would be on the MHC molecules, which then can be presented to T and B cells.

What would change on these molecule during a measles infection from non-infected?

MHC class I (endogenous antigens)

Which MHC molecule would most likely display a viral peptide?

MHC class II (exogenous antigens)

Which MHC molecule would most likely display an extra-cellular bacterial peptide?

Cytotoxic T cells

Which T cell recognizes MHC class I?

Helper T cells

Which T cell recognizes MHC class II?

Activated

1. A lymphocyte that is able to proliferate because it has received the necessary signals and its antigen receptor has bound an antigen. To activate a naive B cell, the antigen has to bind the B cell receptor and a helper T cell usually has to confirm the antigen needs to be eliminated via a cytokine. 2. To activate a T cell, a dendritic cell (innate immune system) presents the antigen to the cell along with the stimulatory signals. Recognition of the antigen (MHCI or MHCII) by the T cell (TCR+CD4/CD8) serves as the first signal. The stimulatory signals (B7) of the dendritic cell/ APC binding to CD28 on the T cell serves as the second signal confirming the antigen is an invader. When a naive cell receives the signal and antigen, it becomes activated, forming millions of progeny.

perforin

1. A molecule that forms pores in the target cell membrane

Activation (clonal selection)

1. Activated B cells: These can proliferate because their B cell receptors are bound to antigen X and the cells have received required signals from T helper cells.

Effector cells (clonal selection)

1. Antibodies: These neutralize the invader and tag it for destruction

Effector B cell (fully activated)

1. B cell: also called plasma cells; they make Y shaped proteins called antibodies that protect the body by binding to antigens. The ends of the antibodies attach to the antigen, while the stem of the antibody tags the antigen for rapid elimination. This is part of humoral immunity, since B cells and antibodies eliminate antigens and toxins that are extracellular in the bloodstream or tissue fluids (they are not within the host cell).

T regulatory (Treg) cells

1. CD4+ cells that respond to antigen presenting cells not expressing co stimulatory molecules. The role of T regulatory cells is to prevent certain immune response, which allows for developing tolerance. 2. Stop the immune response from continuing (IL-10, TGF-beta)

Peyer's Patch

1. Collection of lymphoid cells in the gastrointestinal tract; part of the mucosa-associated lymphoid tissue. Specialized epithelial cells called M cells transfer material from the intestinal lumen to the Peyer's patches. Additionally, dendritic cells in and near Peyer's patches can also reach through the epithelial layer and grab material in the intestine to present it to lymphocytes.

Effector

1. Differentiated descendant of an activated lymphocyte; it has properties that allow it to help eliminate the antigen. Activated B cell differentiate to become plasma cells, which is the effector form of a B cell that is an antibody- secreting factor. Antibodies bind to antigens, tagging the antigen for elimination by macrophages and other components of the immune system. 2. Activated T cell differentiate to become either Cytotoxic T cells or Helper T cells. Effector forms of a cytotoxic T cell induce apoptosis in infected or cancerous self cells. 3.The other effector form is helper T cell, which activate B cells and macrophages, and release cytokines that stimulate other parts of the immune system (including other T cells)

TFH

1. Follicular B helper T cells that are found in the B cell follicles of secondary lymphoid organs that produce cytokines to help activate B cells. 2. Responsible for migrating into the B follicle and activating B cells.

Development (clonal selection)

1. Immature B cells: As these develop, a functionally limitless assortment of B-cell receptors is randomly generated 2. Naive B cells: Each cell is programmed to recognize a specific epitope on an antigen; B cell receptors guide that recognition.

How is lymph created?

1. Lymph forms as a result of the body's circulation system. As blood enters the capillaries, some of the liquid is forced out to join the tissue fluid (the extracellular fluid that bathes the tissues). Some re-enter the capillaries, but some is left in the tissues. Excess tissue fluid enters lymphatic vessels, carrying various antigens and other materials (including leukocytes) along with it to become lymph, which is a colorless fluid derived from tissue fluid. As the lymph is pushed through the lymphatic vessels, it passes through lymph nodes, a type of secondary lymphoid organ.

Naive lymphocyte

1. Lymphocytes that have an antigen receptor, but have not yet encountered the antigen recognized by the receptor 2. To activate a naive B cell, the antigen has to bind to the B cell receptor and a helper T cell usually has to confirm the antigen needs to be eliminated via a cytokine. 3. To activate a naive T cell, a dendritic cell (innate immune system) presents the antigen to the cell along with stimulatory signal (B7). Recognition of the antigen (MHCI or MHCII) by the T cell (TCR+CD4/CD8) serves as the first signal. The stimulatory signals (B7) of the dendritic cell/ APC binding to CD28 on the T cell serves as the second signal confirming the antigen is an invader.

Secondary lymphoid organs

1. Peripheral lymphoid organs where lymphocytes function in immune response; they include the adenoids, tonsils, spleen, appendix, and lymph nodes, among others. 2. The purpose of the secondary lymphatic organs is to bring antigens into contact with a dense population of lymphocytes. Only in secondary lymphatic organs can cells of the immune system interact and transfer cytokines to initiate an adaptive immune response. 3. Spleen is a secondary lymphatic organ of the blood.

Proliferation and Differentiation (clonal selection)

1. Plasma (effector B cells): These descendants of activated B cells secrete large quantities of antibody molecules that bind to antigen X when it is encountered again. 2. Memory B cells: These long lived descendants of activated B cells recognize antigen X when it encountered again.

T cytotoxic cell

1. T cytotoxic cell induces apoptosis of infected or cancerous self-cells. This a form of cell mediated immunity because because it deals with microbial invaders within a host cell.

TH1

1. T helper cells that produce cytokines that promote a response effective against intracellular invaders by activating macrophages and stimulate T cytotoxic cells. 2. APC tells these cells that cytotoxic response is needed such as IL-2, IFN-gamma 3. IL-2, IFN-gamma 4. Response to viruses (cytotoxic T cells- IL-2.. IFN- gamma- macrophages)

TH2

1. T helper cells that produce cytokines that promote a response effective against parasitic worms like helminths and multicellular pathogens by recruiting eosinophils and basophils. 2. APC tells this helper T cell that a humoral response is needed (IL-4, IL-5, IL-13) 3. IL-4, IL-5, IL-13 (helminths)

TH17

1. T helper cells that produce cytokines that recruit neutrophils and thereby direct a response against extracellular pathogens 2. Initiate an inflammatory response (IL-17) 3. Anti-bacterial response through PMNs

Primary response

1. The adaptive immune system's first response/encounter to a particular antigen

Secondary Response

1. The enhanced immune response that occurs upon second or subsequent exposure to specific antigen, caused by the rapid activation of long-lived memory cells. This response is faster and more efficient than the primary response.

Proteases

1. The pores by perforin allow these to enter the target cell, where they cause reactions that induce cell to undergo apoptosis.

How many peptides can MHC molecules display over the course of a human life?

1. There are three loci of MHC class I genes, designated HLA-A, HLA-B, HLA-C. 2. There are at least 890 alleles for HLA-A, 1420 for HLA-B, and 620 for HLA-C. In addition, the loci are all co-dominantly expressed. In other words, you inherit three MHC class I genes from mom and three from dad that are co-dominantly expressed

Primary lymphatic organ

1. Thymus and bone marrow 2. location where lymphocytes mature. It is the site where hematopoietic stem cells reside and give rise to all blood cells. 3.B cells mature in bone marrow. T cells mature in the thymus. They then migrate to secondary lymphatic organs, waiting to encounter an antigen.

T helper cell

1. Type of lymphocyte programmed to activate B cells and macrophages via cytokines, and assist other parts of the immune system via cytokines (including other T cells)

T regulatory cells

1. Type of lymphocyte that helps control the immune response. They prevent the immune system from overreacting and responding to harmless substances

Lymph node

1. contains lymphocytes and are bean shaped structures that filter substances that travel in lymphatic vessels.

Memory cells

1. long lived descendants of activated lymphocytes that can quickly respond when a specific antigen is encountered again. They are responsible for the effectiveness of the secondary response. Some activate B cells differentiate into memory B cells that respond more efficiently to a later exposure to the same antigen in a secondary response. Some activated T cells differentiate into memory cytotoxic T cells and memory helper T cells.