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Pathophysiology > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

Adaptive Immunity

A

The third line of defense in the human body
- Once barriers (1st line) and inflammation (2nd line), the adaptive immune response is called into action
- Augments the initial defenses against infection and provides long-term security against reinfection

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2
Q

Humoral Immunity

A

Is the aspect of the immune system that synthesizes immunoglobulins
Humoral = Antibodies

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3
Q

Cellular Immunity

A
  • Does not synthesize antibodies
  • Driven by T cells
  • Works by the release of cytokines and phagocytes
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4
Q

Active vs. Passive Immunity

A

Active immunity is produced by an individual either after natural exposure to an antigen or after immunization, whereas passive immunity does not involve the host’s immune response at all

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5
Q

What are antigens?

A

A molecule that can react with binding sites on antibodies or antigen receptors on B and T cells
- Most, but not all, antigens are also immunogens

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6
Q

What are antibodies?

A

A serum glycoprotein produced by plasma cells in response to a challenge by an immunogen

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7
Q

What are the function of antibodies?

A
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8
Q

IgG

A
  • The most abundant immunoglobulin (76%)
  • Located in plasma, interstitial fluid
  • Only immunoglobulin that crosses placenta
  • Responsible for secondary immune response
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9
Q

IgA

A
  • Accounts for 15% of immunoglobulins
  • Found in body secretions, tears, saliva, breast milk, colostrum
  • Lines mucous membranes and protects body surfaces
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10
Q

IgM

A
  • Accounts for 8% of immunoglobulins
  • Largest immunoglobulin
  • First antibody produced during the initial, or primary, response to antigen
  • Usually synthesized early in neonatal life, but may be increased as a response to infection in utero
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11
Q

IgE

A
  • Lowest amount of immunoglobulin
  • Functions as a mediator of many common allergic responses and in the defense of parasitic infections
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12
Q

IgD

A
  • 1% of immunoglobulins
  • Functions as an antigen receptor on the surface of early B lymphocytes
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13
Q

B-Cell Receptors

A

is a complex of antibody bound to the cell surface and other molecules involved in intracellular signaling
-Its role is to recognize antigen and communicate that information to the cell’s nucleus

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14
Q

T-Cell Receptors

A

is composed of an antibody-like transmembrane protein and a group of accessory proteins that are involved in intracellular signaling
- Similar to the BCR, the TCR is responsible for recognition and binding to the antigen, whereas the accessory proteins are responsible for the intracellular signaling necessary for activation and differentiation of the T cell

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15
Q

Transplantation

A
  • Cells in transplanted tissue or organs from one individual will have a different set of MHC (major histocompatibility complex) surface antigens than those of the recipient; therefore, the recipient can mount an immune response against the foreign MHC antigens, resulting in rejection of transplanted tissue
  • The more similar tow individuals are in their HLA (human leukocyte antigen) tissue type, the more likely a transplant from one to the other will be successful
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16
Q

CD1

A
  • A type of antigen-presenting molecule
  • Have very low genetic polymorphism a structure similar to MHC
  • Found in cells of the thymus
  • Appear to specialize in presenting lipid antigens contained in lipoproteins, glycolipids, and other molecules
  • Very important in infections with Mycobacterium (TB and leprosy) which have a very large amount of lipid in their cell membranes
17
Q

Cytokines

A
  • A large number of cytokines are secreted by APCs and lymphocytes and provide both positive and negative regulation of the immune response
  • Can cause a lymphocyte to proliferate and differentiate
  • The participation of cytokines is essential to the development of an adequate immune response, and in general the precise combination of cytokines influences the ultimate response of a given cell
18
Q

Clonal Diversity and Selection

A
  • During generation of clonal diversity, a large population of T cells and B cells is produced before birth
  • Clonal selection is the process by which antigen selects lymphocytes with complementary TCRs or BCRs and induces an immune response with the production of specific antibody or cytotoxic T cells, or both
19
Q

B Cells

A

Lymphoid stem cells enter bone marrow and differentiate into B lymphocytes
- B cells can differentiate into plasma cells which produce antibodies (immunoglobulins)
- Can differentiate into long-lived memory cells

20
Q

T Cells

A

Lymphoid stem cells that migrate from bone marrow to the thymus and differentiate into T lymphocytes
- T cells make up 70-80% of the circulating lymphocytes and are primarily responsible for immunity to intracellular viruses, tumor cells, and fungi
- T cells live from a few months to the life span of an individual and account for long-term immunity

21
Q

Secondary Lymphoid Organs

A
  • Spleen
  • Lymph nodes
  • Adenoids
  • Tonsils
    -Peyer patches
22
Q

Antigen Processing

A

The process by which phase 2 of adaptive immunity is achieved
- the process requires the cooperation among a variety of cells in the secondary lymphoid organs; most antigens need to be processed by phagocytic cells, primarily dendritic cells, that also present the processed antigen on their surfaces and present the antigen to lymphocytes

23
Q

T-Helper Lymphocytes

A
  • Most immune responses require T-helper cells (Th cells)
  • Precursor Th cells interact with APCs through the TCR-CD4 complex, a variety of adhesion molecules, and cytokines, especially IL-1, and develop into either Th1 or Th2 subsets
  • Th1 cells help activate macrophages and cytotoxic T cells
  • Th2 cells help activate B cells
24
Q

Primary and Secondary Immune Responses

A
  • The primary immune response is the first exposure to the antigen
  • The secondary response has a much higher proportion of IgG relative to IgM
  • The secondary response is much more rapid than the primary response because of the presence of memory cells in the secondary phase
25
Q

Cell Differentiation

A

B cells become activated upon recognition of a particular antigen to proliferate and differentiate either into plasma cells that produce antibodies OR into memory B cells

26
Q

T-Cell Activation

A

Results from recognition by the TCR and CD8 of antigen presented by MHC class I
- Appropriate intercellular adhesion molecules and cytokines, such as IL-2 from Th1 cells, are also necessary for efficient differentiation
- T cells become cytotoxic T lymphocytes (CTLs) or memory T cells

27
Q

Secretory (Mucosal) Immune Response

A

A distinct set of lymphoid tissues makes up another, partially independent, immune system that protects the external surfaces of the body through lacrimal and salivary glands and a network of lymphoid tissues residing in the breast, bronchi, intestines, and GU tract
- lymphocytes destined for the secretory immune system undergo a different pattern of migration to mucosal areas where they undergo clonal selection and maturation
- Plasma cells in those sites secrete antibodies into bodily secretions (tears, sweat, saliva)to prevent pathogenic microorganisms from infecting the body’s surfaces and possibly penetrating to cause systemic disease

28
Q

Tc Lymphocytes

A

T-cytotoxic lymphocytes
- Are responsible for the cell-mediated destruction of tumor cells or cells infected with viruses

29
Q

NK Cells

A
  • Are involved in cell-mediated immunity
  • These cells are not T or B cells but are large lymphocytes with many granules in the cytoplasm
  • NK cells do not need prior sensitization for their generation. These cells are involved in the recognition and killing of virus-infected cells, tumor cells, and transplanted grafts
  • KN cells have a vital role in immune surveillance for malignant cell changes
30
Q

T Regulatory Lymphocytes (Treg)

A
  • are a diverse group of T cells that control the immune response, usually suppressing the response and maintaining tolerance against self-antigens
31
Q

Immune function in fetal and neonatal periods

A
  • The human neonate jas a poorly developed immune response, particularly in the production of IgG
  • The fetus and neonate are protected in utero and during the first few postnatal months by maternal antibody that was actively transported across the placenta
  • The maternal antibodies are slowly catabolized after birth until they disappear altogether by about 10 months of age
  • At birth, total IgG levels in the umbilical cord are near adult levels
  • The neonate begins producing IgG at birth, and the child’s antibodies reach protective levels after about 6 months of age
32
Q

Aging and Immune Function

A
  • T-cell activity is deficient in older adults, and a shift in the balance of T-cell subsets is observed. These changes may result in increased susceptibility to infection
  • Antibody production to specific antigens is inferior, although older adults tend to have increased levels of circulating autoantibodies

Pathophysiology (8 decks)

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