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Adaptive Immunity :the Immune System Flashcards

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
Humoral immunity Memory cells remain in:
Lymphoid tissue ready to respond to subsequent exposure to the same antigen
26
Humoral immunity : self-tolerance Body doesn’t make
Ab against itself
27
Clonal deletion:
-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
B cell receptor (BCR)
Antibody that remains associated with the cytoplasmic membrane of the B lymphocyte
29
BCR
• 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
T cell-independent Antigens
stimulate B cells directly – Larger, repeating – exogenous
31
T-dependent Ags require help of
antigen presenting cells (APCs) and T helper cells to stimulate B cells (phagocytized by a phagocyte – Smaller not as numerous – endogenous
32
Antigen-Presenting Cells
• Digest antigen • Ag fragments on APC surface with MHC – B cells – Dendritic cells – Activated macrophages
33
Interleukin -1
Stimulates TH cells
34
Interleukin-2
Activates TH, B, TC, and NK cells
35
Interleukin- 12
Differentiation of CD4 cells
36
Y-interferon (Gamma)
Stimulate macrophage activity
37
Chemokines
Induce migration of leukocytes to infection
38
MHC (very important in transplants/grafting) Major Histocompatibility complex
in all cells. Accepts or rejects ag as compatible or not. Attaches to non compatible ag and presents it to T cell
39
Activation of B cells w helper T cells
40
Cell mediated immunity
• 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
What are the 3 T cells?
• T Helper Cells (TH) = CD4 cells • T Cytotoxic Cells (TC) = CD8 cells • T Regulatory Cells (Treg)
42
• T Helper Cells (TH) = CD4 cells
present T dependent Ags to B cells, stimulate other T & B cells
43
• T Cytotoxic Cells (TC) = CD8 cells
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
• T Regulatory Cells (Treg)
suppress T cells against self subset of CD4 TH cells formerly called T suppressor cells
45
Humoral vs cellular immune system
46
T cytotoxic cells
47
Primary and Secondary Responses
In humoral immunity the primary response to an antigen occurs when the antigen is first recognized by host B cells
48
Primary response of B cells can occur by two mechanisms
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
Secondary response:
when an antigen recognized by memory cells enters the blood
50
The central role of helper T cells
51
Cell-Mediated Immunity
-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
Cell-Mediated Immune Reaction
• 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
Natural Killer (NK) Cells
Granular leukocytes destroy cells that don’t express MHC I • Kill virus-infected and tumor cells • Attack parasites
54
AIDS destroys TH cells, thereby impairing both humoral and cell-mediated immunity...
Will be affected
55
Cell Mediated Immunity (*know)

Microbiology (22 decks)

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