Lymphoid Tissue: Histology Oms 6120

Front 1

Percentage of Lymphocytes in Thymus

Back 1

100% T Lymphocytes

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Percentage of Lymphocytes in Bone Marrow

Back 2

10% T Lymphocytes, 90% B Lymphocytes

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Percentage of Lymphocytes in Spleen

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45% T Lymphocytes, 55% B Lymphocytes

Front 4

Percentage of Lymphocytes in Lymph Nodes

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60% T Lymphocytes, 40% B Lymphocytes

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Percentage of Lymphocytes in Blood

Back 5

80% T Lymphocytes, 20% B Lymphocytes

Front 6

B Lymphocyte Main Function

Back 6

Carries membrane receptors (IgM). When activated by specific antigens, proliferates by mitosis, differentiating into plasma cells that secrete large amounts of antibodies

Front 7

B Memory Lymphocyte Main Function

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Activated B Cell that is primed to respond more rapidly and to a greater extent upon subsequent exposure to the same antigen.

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T Cytotoxic Lymphocyte Main Function

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Carries TCRs. Specialized to recognize antigens assoc. with MHC-I on the surface of other cells. Produces perforin and other proteins that kill foreign cells, virus infected cells, and some tumor cells.

Front 9

T Helper Lymphocyte Main Function

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Carries TCRs. Modulates other T and B Cells, stimulating their activities.

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T Memory Lymphocyte Main Function

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Carries TCRs. Is primed to respond more rapidly and to a greater extent upon subsequent exposure to the same antigen.

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NK Lymphocyte Main Function

Back 11

Lacks T and B-Cell receptors. Attacks virus-infected cells and cancer cells without previous stimulation.
NK=Natural Killer

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TCR

Back 12

T-Cell Receptor

Front 13

MHC-I

Back 13

Class I Major Histocompatibility Complex

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Gamma/delta (γδ) T Lymphocyte Main Function

Back 14

small population of T cells that have neither CD8 nor CD4 markers on their surface. develop in the thymus and migrate into various epithelial tissues.
strategically positioned at the interfaces of the external and internal environments and function as the first line of defense against invading organisms.
encounter antigen on the surface of the epithelial cells even before it enters the body.

Front 15

CD3 Cell Surface, Ligand and Target Cell, and Function

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1. All T Cells
2. None
3. Transduces epitope-MHC complex bidning into intracellular signal, activating T cell.

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CD4 Cell Surface, Ligand and Target Cell, and Function

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1. T helper Cells
2. MHC II on antigen-presenting cells
3. Coreceptor for TCR binding to epitope-MHC II complex, activation of T helper cell

Front 17

CD8 Cell Surface, Ligand and Target Cell, and Function

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1. Cytotoxic T Cells and Supressor T Cells
2. MHC I on most nucleated cells
3. Coreceptor for TCR binding to epitope-MHC I complex, activation of cytotoxic T cell

Front 18

CD28 Cell Surface, Ligand and Target Cell, and Function

Back 18

1. T Helper Cells
2. B7 on antigen-presenting cells
3. Assists in activation of T helper cells

Front 19

CD40 Cell Surface, Ligand and Target Cell, and Function

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1. B Cells
2. CD40 receptor molecule expressed on activated helper T cells
3. Binding of CD40 to CD40 receptor permits T helper cell to activate B cell to proliferate into B memory cells and plasma cells

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Percentage of IgG in the Adult Blood

Back 20

85%

Front 21

Percentage of IgM in the Adult Blood

Back 21

5-10%

Front 22

Percentage of IgA in the Adult Blood

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5-15%

Front 23

Percentage of IgD in the Adult Blood

Back 23

<1%

Front 24

Percentage of IgE in the Adult Blood

Back 24

<1%

Front 25

Cells that bind via Fc region of IgG

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Macrophages, B cells, NK cells, neutrophils, eosinophils

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Cells that bind via Fc region of IgM

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B Cells

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Cells that bind via Fc region of IgA

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B cells

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Cells that bind via Fc region of IgD

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B cells

Front 29

Cells that bind via Fc region of IgE

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Mast cells, basophils

Front 30

IgG major functions

Back 30

Principal Ig in secondary immune response
longest half life (23 days) of all 5 Igs
activates complement
stimulates chemotaxis
crosses placenta, providing the newborn with passive immunity

Front 31

IgM major functions

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Principal Ig produced during primary immune response
the most efficient Ig in fixing complement
activates macrophages
serves as Ag receptor of B lymphocytes

Front 32

IgA major functions

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Ig present in body secretions (tears, saliva, vaginal fluid, nasal cavity, bronchi, intestine, prostate)
protection against proliferation of microorganisms in these fluids and aids in the defense against microbes and foreign molecules penetrating the body via cells lining these cavities

Front 33

IgD major functions

Back 33

acts an an antigen receptor (with IgM) on the surface of mature B lymphocytes (only traces in serum)

Front 34

IgE major functions

Back 34

stimulates mast cells to relase histamine, heparin, leukotrines, SRS-Ac, and eosinophil chemotactic factor of anaphylaxis
responsible for anaphylactic hypersensitivity reactions
increased levels in parasitic infections

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Describe Innate Immunity

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non specific, immediate backup, protective mechanism to provide immediate backup support to initial physical and biochemical barriers that the body presents to invasion and disease

Front 36

Describe Adaptive/Acquired Immunity

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specific, very important, mechanisms that allow the body to fine-tune and anticipate attacks
a. primary adaptive response
b. secondary adaptive response

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Cells That Participate in Innate Immunity

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Mast cells trigger to “loosen” the endothelial barrier

Front 38

How Antibodies and Complement Bind to the Antigens Protecting the Organism

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1- agglutination of Abs
2- opsonization of microorganism stimulates phagocytosis
3- neutralization with binding Abs inactivates toxins and blocks bacterial cell adhesions
4- cytotoxicity mediated by cells
5- complement activation where binding Abs triggers cascade to yield cell lysis.

Front 39

Humoral (antibody-mediated) Immunity

Back 39

mediated by antibodies that act directly on an invading agent.
These antibodies are produced by B lymphocytes and by plasma cells derived from B lymphocytes.
The effectiveness of this passive transfer proves that it is the antibody that is responsible for the protection

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Cell-mediated immunity

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mediated by specific T lymphocytes that attack and destroy virus-infected host cells or foreign cells.
important in the defense against viral, fungal, and mycobacterial infections, as well as tumor cells.
also responsible for transplant rejection.

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Primary Immune Response

Back 41

refers to the body's first encounter with an antigen.
characterized by a lag period of several days before antibodies (mostly IgM) or specific lymphocytes directed against the invading antigen can be detected in the blood.
The initial response to an antigen is initiated by only one or a few B lymphocytes that have been genetically programmed to respond to that specific antigen.
After this initial immune response, a few antigen-specific B lymphocytes remain in circulation as memory cells.

Front 42

Secondary Immune Response

Back 42

usually more rapid and more intense than the primary response, because of the presence of specific memory B lymphocytes already programmed to respond to that specific antigen.
higher levels of secreted antibodies (usually IgG)
the basis of most immunizations and vaccinations
Some antigens may produce a hypersensitivity reaction or even anaphylaxis
antibodies themselves do not kill or destroy invading antigens; they simply mark them for destruction by cells of the immune system.

Front 43

IL-2 Source, Functions

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1. CD4+ T cells
2. Induces proliferation and differentiation of CD4+ T cells and to a lesser degree CD8+ T cells, B cells, and NK cells

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IL-4 Source, Functions

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1. CD4+ T cells, mast cells
2. Induces proliferation and differentiation of B cells, CD4+ T cells; activates macrophages, promotes synthesis of IgE and IgG

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IL-5 Source, Functions

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1. CD4+ T cells
2. Induces proliferation and differentiation of eosinophils; stimulates B cells to secrete IgA

Front 46

IL-6 Source, Functions

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1. Endothelial cells, neutrophils, macrophages, T cells
2. Stimulates differentiation of hematopoietic cells; induces growth of activated B cells

Front 47

Thymus Structural Features

Back 47

Cortex and Medulla: Yes
Lymphoid Nodules: No
Capsule: Yes
Cords/Sinuses: No
Lymphatic Vessels: only some efferent
HEV: No
Unique Feature: Hassall's Corpuscles

Front 48

MALT (Peyer's Patches) Structural Features

Back 48

Cortex and Medulla: No
Lymphoid Nodules: Yes
Capsule: No
Cords/Sinuses: No
Lymphatic Vessels: efferent only
HEV: Yes
Unique Feature: located in wall of ileum

Front 49

Tonsil (Palatine) Structural Features

Back 49

Cortex and Medulla: No
Lymphoid Nodules: Yes
Capsule: Partial
Cords/Sinuses: No
Lymphatic Vessels: efferent only
HEV: Yes
Unique Feature: in mucosa of pharynx

Front 50

Lymph Node Structural Features

Back 50

Cortex and Medulla: Yes
Lymphoid Nodules: Yes
Capsule: Yes
Cords/Sinuses: Yes
Lymphatic Vessels: afferent and efferent
HEV: Yes
Unique Feature: cortical nodules and subscapular sinus

Front 51

Spleen Structural Features

Back 51

Cortex and Medulla: No
Lymphoid Nodules: Yes
Capsule: Yes
Cords/Sinuses: Yes
Lymphatic Vessels: a few efferent only
HEV: No
Unique Feature: central arteries and red pulp