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Microbiology > Bacterial Defense System > Flashcards

Bacterial Defense System Flashcards

1
Q

What are the features of the adaptive immune response?

A

Specificity, Memory, and Tolerance

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2
Q

Explain specificity

A

Immune cells recognize and react with individual molecules (antigens) via direct molecular interactions

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3
Q

Explain the memory feature of the adaptive immune response

A

The immune response to a specific molecule is faster and stronger upon subsequent exposure because the initial antigen exposure induced growth and division of antigen-reactive cells, resulting in multiple copies of antigen-reactive cells.

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4
Q

Explain the tolerance feature of the adaptive immune response

A

immune cells are not able to react with self antigen. Self-reactive clones are destroyed during development of the immune response.

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5
Q

What is an antigen?

A

An antigen is anything the immune system recognizes as foreign. Reacts with an epitope ( short group or sequence of 4-6 amino acids).

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6
Q

What are antibodies?

A

Protein complexes that play a central role in both the specific and nonspecific immune system.
-produced by B-cells
-recognize specific regions of molecules called epitopes (the very tips)

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7
Q

What are the two different ways an antibody can bind to an antigen?

A

-Linear Sequence Determinants: A sequence of amino acids
-conformational Determinants: a group of amino acids that are close together when the antigen is folded.

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8
Q

What are lymphocytes and what two forms do they come in?

A

-Lymphocytes are antigen-specific leukocytes
-T-cells that mature in the thymus
-B-cells that mature in the bone marrow

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9
Q

What are B-cells?

A

-B is for bone marrow
-responsible for antigen interactions, antibody production, and immune memory (reminds what microbe is dangerous)
-have immunoglobulin (Ig0 molecules that are copies of the type of antibody the B-cell will produce and are on the surface

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10
Q

What happens to the B-cell after it is exposed to antigens?

A

They are split into memory cells or plasma cells
-Memory cells are long lived and can remain in the cortex for years
-plasma cells are differentiated antibody producing cells that only live for a few days (located in the medulla of the lymph node)

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11
Q

What are T-cells?

A

-T-cells are produced in the thymus

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12
Q

What are T-cell receptors (TCRs)

A

All T-cells have antigen-specific T-cell receptors on their surface and interact specifically with antigen.
Note: The antigen is always presented in processed form to the TCR by another cell-the aptly named antigen presenting cell or APC

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13
Q

What are the two types of APCs

A

-The amateurs: infected cells that present internally made foreign proteins (react for survival)
-The professionals (immune cells): phagocytes cells (macrophages) that ingest foreign particles and present proteolyses components on cell membrane (do it on purpose)

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14
Q

What are the two types of T-cells

A

-CD4 positive T helper cells
-CD8 positive cytotoxic T-cells

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15
Q

What are cytotoxic T cells?

A

CD8 positive cytotoxic T cells (CTLs) kill antigen bearing cells directly through interaction between a cell surface antigen on the target cell and the TCR (look at slide 28 to see how it works)

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16
Q

What are the two types of Helper T cells?

A

-TH1 cells: are responsible for recruiting and activating nonspecific effector cells like phagocytes (T inflammatory cells/ signals body to respond to antigen)
-TH2 cells: stimulate B lymphocytes to produce antibodies (signals to B-cells they have been infected w/antigens.

17
Q

Where are T-cell receptors (TCRs) expressed and what do they consist of?

A

-TCR is expressed on the surface of all T cells -It consist of a constant region and a variable region that can bind specific antigens when they are presented on the surface of an MHC
-Like Igs, the variable region can recognize millions of different antigens

18
Q

What are the two types of Major Histocompatibility Complex (MHC)

A

-Class I: which are on the surface of the amateur APCs (antigen presenting cells)
-Class II: on the. Surface of professional APCs like macrophages
NOTE: individual MHCs recognize a wide variety of antigens relative to Igs and TCRs

19
Q

What happens between MHC class I APCs and Cytotoxic T cells

A

-Team up against intracellular pathogens and cancer cells-Class I MHCs present antigen that have been processed by the host degradation machinery and are bound by MHC class I in the ER
- MHC class I presenting antigen on the surface of a host cell interacts with TCR on the surface of cytotoxic T cells

20
Q

What happens between MHC class II APCs and helper T cells?

A

-extracellular pathogens engulfed by phagocytes
-Class II MHCs bound to a self-peptide (li) line the inner surface of lysosomes of phagocytes cells (professional APCs)
-Foreign peptides formed from the degradation of the pathogen in the phagolysosome displace li and the complex is displaced to the surface of the APC
-MHC class IIs bound to antigen on the surface of the APC are recognized by T helper cells

21
Q

What are Interleukins?

A

Cytokines that mediate interactions between leukocytes (how leukocytes talk to each other/ communication between white blood cells)

22
Q

What is Interleukin 1 (IL-1) do?

A

-secreted by macrophages
-signals TH cells to make more TH cells

23
Q

What is IL-2

A

-Produced by activated TH cell in response to IL-1(the signal)
-Binds to IL-2R on surface of TH cell
-Induces cell to divide and make clonal copies

24
Q

What is IL-4?

A

-Produced by activated TH cells in response to IL-1 and IL-2
-Binds to IL-4R on B-cells
-Stimulates B cells to proliferate and differentiate into antibody producing plasma cells

25
Q

What is Precise Definition (Cell mediated Immunity)

A

Any immune response that involves antigen-specific cells of the immune system but where antibody production or activity is not important

26
Q

What is Working definition (cell mediated immunity)

A

Cell mediated immunity can only be transferred between animals by transferring lymphocytes

27
Q

What is primary Response?

A

TH2 cell activated by APC presenting MHC II activated B-cell with same MHC II antigen complex on its surface

28
Q

What is direct B-cell Stimulation?

A

In second encounter with antigen, antigen binding to antibodies on B-cell surface activate B-cell directly. This response is much more rapid.

29
Q

What is the antibody primary response?

A

Following antigen introduction there is a latent period before a specific antibody appears in the blood. This is followed by a gradual increase in antibody titer and then a slow fall.

30
Q

What is the antibody secondary response?

A

When a second exposure to antigen occurs several days or weeks later the antibody titer rises rapidly to 10 to 100 times that of the primary response.

Microbiology (6 decks)

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