Adaptive Immunity :the Immune System Flashcards

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1
Q

Immunity

A

Specific antibody and lymphocyte response to an antigen

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2
Q

Antigen (Ag)

A

A substance the body identifies as foreign and to which it produces specific antibodies or sensitized Tcells

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3
Q

Antibody (Ab)

A

Proteins made in response to an antigen

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4
Q

Humoral immunity

A

carried out by antibodies circulating in the blood.
Antibodies are produced by B lymphocytes that have matured into plasma cells

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5
Q

Cell mediated immunity :

A

carried out by T lymphocytes and occurs at the cellular level

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6
Q

Antigen:

A

a substance the body identifies as foreign and toward which it mounts an immune response
• Most are large, complex proteins

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7
Q

Hapten

A

a small molecule that can act as an antigen if it binds to a larger protein molecule (ex: penicillin)

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8
Q

Antibody

A

A protein produced in response to an antigen and is capable of binding specifically to the antigen

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9
Q

Antibodies are produced by

A

Plasma cells ( matured from B cells)

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10
Q

A typical antigen:

A

antibody reaction: gram-negative bacterial pathogen may have several antigens, or immunogens (flagella, pili and cell wall)

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11
Q

Antibodies recognize and react with

A

Antigenic determinants or epitopes

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12
Q

5 classes of immunoglobulins (Igs)

A
  • IgG
  • IgM
  • IgA
  • IgE
  • IgD
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13
Q

IgG antibodies:

A

• Main class of Ab in blood (80% of serum antibodies)
• Only Ig that crosses placenta
• Monomer

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14
Q

IgM antibodies

A

• First Ab produced in response to infection
• 5-10% of serum antibodies
• Pentamer

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15
Q

Primary Response to an Ag:

A

first contact with Ag is characterized by IgM followed by IgG

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16
Q

Secondary response to an Ag (memory):

A

2nd exposure to same Ag, the response is rapid & results in high Ab titer (mostly IgG)

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17
Q

IgA antibodies

A

• In secretions (tears, colostrum, saliva, mucus)
• 10-15% of serum
antibodies
• Dimer

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18
Q

IgE antibodies

A

• Allergic reactions; lysis of parasitic worms
• On mast cells and basophils
• 0.002% of serum antibodies
• Monomer

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19
Q

IgD antibodies

A

• On B cells, initiate immune response
• Monomer
• 0.2% of seum Abs

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20
Q

Specific immune responses are carried out by

A

lymphocytes which develop from stem cells
(as do other WBCs, RBCs, and platelets)
• B lymphocytes (B cells)
• T lymphocytes ( T cells)

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21
Q

Differentiation of T AND B cells

A
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22
Q

Clonal selection:
B cells become activated when an Ag reacts with:

A

Specific receptors on its surface

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23
Q

Clonal selection:
The activated B cell produces:

A

A clone of plasma cells and memory cells

24
Q

Humoral immunity:
Plasma cells…

A

Synthesize and release antibodies

25
Q

Humoral immunity
Memory cells remain in:

A

Lymphoid tissue ready to respond to subsequent exposure to the same antigen

26
Q

Humoral immunity : self-tolerance
Body doesn’t make

A

Ab against itself

27
Q

Clonal deletion:

A

-the process of destroying B and T cells that react to self antigens
this process takes place in the bone marrow and thymus. Removes those lymphocytes that have receptors for self antigens

28
Q

B cell receptor (BCR)

A

Antibody that remains associated with the
cytoplasmic membrane of the B lymphocyte

29
Q

BCR

A

• Each B lymphocyte has multiple copies of a single type of BCR
• Antigen binding site is identical to that of the secreted antibody for that particular cell
• Each BCR is complementary to only one antigenic determinant
• The BCRs on all of an individual’s B cells are capable of recognizing millions of different antigenic determinants (EACH INDIVIDUAL B CELL RECEPTOR)

30
Q

T cell-independent Antigens

A

stimulate B cells directly
– Larger, repeating
– exogenous

31
Q

T-dependent Ags require help of

A

antigen presenting cells (APCs) and T helper cells to stimulate B cells (phagocytized by a phagocyte

– Smaller not as numerous
– endogenous

32
Q

Antigen-Presenting Cells

A

• Digest antigen
• Ag fragments on APC surface with MHC – B cells
– Dendritic cells
– Activated macrophages

33
Q

Interleukin -1

A

Stimulates TH cells

34
Q

Interleukin-2

A

Activates TH, B, TC, and NK cells

35
Q

Interleukin- 12

A

Differentiation of CD4 cells

36
Q

Y-interferon
(Gamma)

A

Stimulate macrophage activity

37
Q

Chemokines

A

Induce migration of leukocytes to infection

38
Q

MHC (very important in transplants/grafting)
Major Histocompatibility complex

A

in all cells. Accepts or rejects ag as compatible or not. Attaches to non compatible ag and presents it to T cell

39
Q

Activation of B cells w helper T cells

A
40
Q

Cell mediated immunity

A

• Involves the direct actions of T cells
• T cells respond to intracellular (endogenous) Ags, viruses, tumors and reject transplanted tissue
• Some activated T cells become memory cells

41
Q

What are the 3 T cells?

A

• T Helper Cells (TH) = CD4 cells

• T Cytotoxic Cells (TC) = CD8 cells

• T Regulatory Cells (Treg)

42
Q

• T Helper Cells (TH) = CD4 cells

A

present T dependent Ags to B cells, stimulate other T & B cells

43
Q

• T Cytotoxic Cells (TC) = CD8 cells

A

differentiate into cytotoxic T Lymphocytes (CTL) which destroy target cells with perforin

differentiate into cytotoxic T Lymphocytes (CTL) which destroy target cells with perforin

44
Q

• T Regulatory Cells (Treg)

A

suppress T cells against self
subset of CD4 TH cells
formerly called T suppressor cells

45
Q

Humoral vs cellular immune system

A
46
Q

T cytotoxic cells

A
47
Q

Primary and Secondary Responses

A

In humoral immunity the primary response to an antigen occurs when the antigen is first recognized by host B cells

48
Q

Primary response of B cells can occur by two mechanisms

A

B cells can be activated by binding antigen, proliferating and forming plasma cells (T-independent antigens)
Produces IgM antibody and no B memory cells are formed (T-dependent antigens)

49
Q

Secondary response:

A

when an antigen recognized by memory cells enters the blood

50
Q

The central role of helper T cells

A
51
Q

Cell-Mediated Immunity

A

-Involves the direct actions of T cells(makes memory cells and clones themselves
• T cells interact directly with other cells that display foreign antigens
• Involves the differentiation and actions of different types of t cells Th2, Tc and Tm
• Involves production of chemical mediators (cytokines)
– Cytokines: lymphokines and interleukins

52
Q

Cell-Mediated Immune Reaction

A

• Involves the response of T lymphocytes
• T cells cannot be activated directly by antigens
• Macrophages that have processed an antigen secrete the lymphokine interleukin-1 (IL-1), which activates T helper cells
• T helper cells secrete interleukin-2 (IL-2) and activate delayed hypersensitivity cells and cytotoxic killer cells
• IL-1 and IL-2 cause undifferentiated cells to become natural killer cells

53
Q

Natural Killer (NK) Cells

A

Granular leukocytes destroy cells that don’t express MHC I
• Kill virus-infected and tumor cells • Attack parasites

54
Q

AIDS destroys TH cells, thereby impairing both humoral and cell-mediated immunity…

A

Will be affected

55
Q

Cell Mediated Immunity (*know)

A