Adaptive Immunity Flashcards

1
Q

What are the three general aspects of adaptive immunity?

A

Systemic effect, Specificity, Memory

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2
Q

What is cellular (cell-mediated) immunity?

A
  • Lymphocytes directly attack and destroy foreign cells or diseased host cell
  • Rids the body of pathogens that reside inside human cells
  • Kills cells that harbor them
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3
Q

What is humoral (antibody-mediated) immunity?

A
  • Mediated by antibodies that do not directly destroy a pathogen but tag it for destruction
  • Many antibodies are dissolved in body fluids
  • Effective against extracellular viruses, bacteria, yeasts, protozoans, and molecular disease agents such as toxins, venoms, and allergens.
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4
Q

What is an antigen?

A

Any molecule that triggers an immune response - characteristics enable body to distinguish “self” molecules from foreign ones.

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5
Q

What are epitopes (antigenic determinants)?

A

Certain regions of an antigen molecule that stimulate immune responses - one antigen molecule typically has several epitopes that can stimulate the simultaneous production of different antibodies.

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6
Q

What do haptens do?

A

Trigger immune response by combining with a host marcomolecule and creating a complex that the body recognizes as foreign.

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7
Q

What are antibodies?

A

Antibodies, also known as immunoglobulins, are a defensive gamma globulin found in blood plasma, tissue fluid, body secretions, and some leukocyte membranes.

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8
Q

Describe the structure of a antibody monomer.

A

Composed of four polypeptide chains linked by disulfide bonds. Two larger heavy chains have a hinge region where antibody is bent. Two light chains gives the antibody its uniqueness. Constant

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9
Q

Describe the antigen-binding site.

A

Formed from the V regions of the heavy and light chain on each arm. Attaches to the epitope of an antigen molecule.

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10
Q

Somatic recombination

A

DNA segments shuffled and form new combinations of base sequences to produce antibody genes.

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11
Q

Somatic hypermutation

A

B cells in lymph nodules rapidly mutate creating new sequences

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12
Q

What are the three types of lymphocytes?

A

Natural kill (NK) cells, T lymphocytes (T cells), B lymphocytes (B cells)

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13
Q

Describe positive selection (T cells)

A

Positive selection testes CD4+ and CD8+ thymocytes to determine if they bind to major histocompatibility complex (MHC) class 1 or MHC class 2 molecules, displayed on thymic epithelial cells. (CD8+ binds to MHC class 1& CD4+ binds to MHC class ). Occurs in thymus cortex.

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14
Q

Describe negative selection (T cells)

A

Negative selection tests the ability of CD4+ and CD8+ thymocytes to tolerate self-antigens. Thymic dendritic cells display self-antigens on MHC complexes. Thymocytes that bind self-antigens with their TCRs are destroyed, while surviving thymocytes continue maturing. Occurs in the medullary region of the thymus.

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15
Q

What are antigen-presenting cells?

A

A cell that phagocytizes an antigen and displays fragments of it on its surface for recognition by other cells of the immune system; chiefly macrophages and B lymphocytes - T cells cannot recognize antigens on their own.

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16
Q

What are cytotoxic T cells?

A

“Effectors” of cellular immunity; carry out attack on enemy cells – respond to endogenous foreign antigens bond to MHC class 1 molecules present on the membrane of an unhealthy cell.

17
Q

What are helper T cells?

A

Help promote cytotoxic T cell and B cell action and innate immunity - interact with specific exogenous antigens bound to MHC class 2 molecules displayed by professional antigen-presenting cells (APC)

18
Q

Where do memory T cells descend from?

A

They descend from cytotoxic T cells.

19
Q

What is humoral immunity?

A

A more indirect method of defense than cellular immunity; B lymphocytes of humoral immunity produce antibodies that bind to antigens and tag them for destruction by other means

20
Q

Describe recognition in humoral immunity.

A

Immunocompetent B cell has thousands of surface receptors for one antigen. Activation begins when an antigen binds to several of these receptors, links them together, and is taken into the cell by receptor-mediated endocytosis. B cell processes the antigen and displays on cell surface.

21
Q

In what three ways does the Fab region of the antibody interact with antigens?

A

Neutralization: Fab covers the antigenic regions
Agglutination: antigen-Fab binds, causing cross-linking of the cells
Precipitation: Fab links circulating soluble particles, forming an insoluble complex

22
Q
A