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81 Cards in this Set
- Front
- Back
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What was a key development in vertebrate immune systems? |
the evolution of lymphoid cells (produce the high degree of specificity) and lymphoid organs |
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How do cells of the immune system arise |
From pluripotent stem cells through two main lines of differentiation in the bone marrow: either myeloid or lymphoid |
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Name for immune cells of interest |
Leukocytes |
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cytokine |
chemical mediators that influence stages of differentiation and maturation |
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Groups of cells produced by the lymphoid lineage |
- T lymphocytes - B lymphocytes ** can both recognize antigen |
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Travel from bone marrow to thymus for differentiation and maturation |
T cells
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Differentiate and mature in fetal liver and adult bone marrow |
B cells |
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Sites of lymphocyte differentiation |
Central or peripheral lymphoid organs |
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Natural killer cells (NK) |
- originate in bone marrow - DO NOT express antigen receptors - important component of innate/natural immunity - Larger that T or B lymphocytes and more granular - AKA 'LGL' large granular lmyphocytes |
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Phagocytes |
- originate in bone marrow from myeloid progenitor cells |
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Types of phagocytes |
- monocytes/macrophages - polymorphonuclear granulocytes |
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3 Different types of granulocytes |
1. neutrophils 2. basophils 3. eosinophils |
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Role of polymorphonuclear granulocytes |
- inflammation and natural immunity - eliminate microbes and dead cells/tissues |
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% of circulating leukocytes that are granulocytes |
50-70% |
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Neutrophils |
- Originate: bone marrow - Characteristics: irregular shaped nucleus with multiple lobes - Role: First cell at infection and phagocytosis |
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4 stages of phagocytosis |
1. Chemotaxis 2. Opsonization 3. Ingestion 4. Digestion |
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Chemotaxis |
movement of cells to site of infection |
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Opsonization |
adherence of cells to foreign agent |
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Ingestion |
the cell engulfs the coated particle - particle becomes enclosed within a phagosome |
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Digestion |
- digestion of ingested microbe by enzymes - Lysosomal enzymes: directly kill or help digest dead organisms - oxidative respiratory burst: oxygen consumption increases 100 fold generating large quantities of hydrogen peroxide (highly toxic) |
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Eosinophil |
- Origin: Bone marrow (white blood cells) - Characteristics: Irregular shaped nucleus - wrights stain = red - Role: antiparisitic/ allergic response - produces high levels of IgE - growth and differentiation stimulated by T-cell derived cytokine (IL-5) |
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% of circulating leukocytes that are eosinophils |
2-5% |
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Basophile/Mast Cell |
- Origin: Circulating counterpart of tissue mast cells. - Characteristics: similar to neutrophil, irregular sac, wrights stain = blue/black - Role: high affinity receptors for IgE |
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Monocytes/macrophages |
- Origin: bone marrow - Characteristics: variable shape and have minute granules - Role: phagocytosis, antigen presentation - can live for months or years - large number of macrophages seen in spleen, lymph nodes and bone marrow |
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% of circulating leukocytes that are monocytes |
5-8% |
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% of circulating leukocytes that are basophiles |
<1% |
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How are macrophages important cells for specific immunity |
- initiate immune response by presenting antigen to antigen-sensitive cells (t-lymphocytes) - can process and present antigen on cell surface - can express secreted and membrane bound proteins that promote t lymphocyte activation |
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Accessory Cells |
- non lymphoid cells - no specificity for different antigens - necessary in immune response |
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Antigen presenting cells (APCs) |
- found in skin, lymph nodes, spleen and thymus - some induce functional activity of t lymphocytes, others communicate with other leukocytes |
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Langerhans' cells in the skin |
provide mechanism for carrying antigen from skin to the T cells located in the lymph nodes where specific immune response is initiated |
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Follicular dendritic cells |
capable of presenting antigen to T cells |
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Lymphoid cells |
- only cells in the body capable of specifically recognizing and distinguishing different antigenic determinants -surface markers differentiate into functional subsets |
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T Lymphocytes |
- 70% of circulating lymphoid pool - long lived - crucial to cell mediated immunity |
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4 subgroups of T lymphocytes |
1. Helper Cells 2. Cytolytic cells 3. Regulatory T cells 4. Memory cells |
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Helper T cells |
- central cells of immune response - secret cytokines that promote proliferation and differentiation of T cells |
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Helper T cell cytokines |
recruit and activate inflammatory leukocytes that provide link between specific T cell immunity and one form of natural immunity (inflammatory response) - most express CD4 |
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Cytolytic T Cells |
lyse cells that produce foreign antigens - most express CD8 |
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Regulatory T cells |
inhibit the immune response and play a role in tolerance to self-antigens |
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Memory T cells |
long lived cells that remember stimulation by an antigen (when re-exposed immune response will happen quicker) |
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B lymphocytes |
- only cells capable of producing antibodies - 10-20% of circulating leukocytes - shorter lived cells (except memory) - antigen recep. of b cells are membrane bound antibodies |
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cognitive cells |
cell that recognizes antigen |
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effector cells |
cell that can eliminate antigen |
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Plasma cells |
- activated b lymphocytes can differentiate into plasma cells - produce and secrete antibodies - Found only in lymphoid organs and at sites of immune responses - do not normally circulate in the blood - exist solely as factories for antibody synthesis and secretion |
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Memory cells |
- capable of surviving long periods - crucial to success of vaccination as well as re-exposure |
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Natural killer (NK) cells |
- major role in innate immunity - no conventional antigen receptors - do posses other CD markers - ability to kill tumor cells that are cytotoxic for virus infected cells and to targets coated with IgG |
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2 types of lymphoid tissues |
1. Central: bone marrow and thymus 2. Peripheral: lymph nodes and spleen |
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Central Lymphoid tissue: bone marrow |
- cell production in red marrow (medullary hematopoiesis) - negative selection takes place so that only 25% of b cells produced live and exit the bone marrow |
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Immunology |
Study of reaction when a host encounters a foreign substance (antigen) |
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Immunology |
Study of reaction when a host encounters a foreign substance (antigen) |
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Immune system |
System within an individual that discriminates between self and non self |
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Immune response |
Reaction from the immune system when a foreign substance invades |
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Immunity |
Discrimination of self and non self |
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Innate/natural/nonspecific immunity |
- available quickly - not specific to pathogen in question |
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Adaptive/acquired/specific immunity |
- specific, separate reaction for individual pathogens - large scope, reactions to many different pathogens - memory, improves with subsequent exposure |
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Adaptive/acquired/specific immunity |
- specific, separate reaction for individual pathogens - large scope, reactions to many different pathogens - memory, improves with subsequent exposure |
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Active immunity |
Antibodies are produced by the individual in response to an outside source (infection) |
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Example of natural active immunity |
Chicken pox |
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Example of artificial active immunity |
Influenza vaccine |
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Example of artificial active immunity |
Influenza vaccine |
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Passive immunity |
Antibodies made outside the individual are then given to the individual to promote protection |
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Example of artificial active immunity |
Influenza vaccine |
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Passive immunity |
Antibodies made outside the individual are then given to the individual to promote protection |
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Example of natural passive immunity |
Antibodies from mother passed to fetus during gestation |
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Example of artificial active immunity |
Influenza vaccine |
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Passive immunity |
Antibodies made outside the individual are then given to the individual to promote protection |
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Example of natural passive immunity |
Antibodies from mother passed to fetus during gestation |
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Example of artificial passive immunity |
Antibodies made outside the individual are injected to help fight infection |
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Humoral immunity |
Serum component |
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Humoral immunity |
Serum component |
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Cell mediated immunity |
All white blood cells, granulocytes (neutrophils, basophils, eosinophils), monocytes, lymphocytes (NK & LAK) - tissue cells: macrophage, mast cells, dendritic |
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Humoral immunity |
Serum component |
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Cell mediated immunity |
All white blood cells, granulocytes (neutrophils, basophils, eosinophils), monocytes, lymphocytes (NK & LAK) - tissue cells: macrophage, mast cells, dendritic |
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2 main lines of differentiation in the immune system |
Myeloid Lymphoid |
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Characteristics of B lymphocyte |
Origin: bone marrow Characteristics: mostly nucleus, very little cytoplasm Role: recognize antigens (called surface immunoglobin), produce antibodies |
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Characteristics of B lymphocyte |
Origin: bone marrow Characteristics: mostly nucleus, very little cytoplasm Role: recognize antigens (called surface immunoglobin), produce antibodies |
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Characteristics of T lymphocytes |
Origin: bone marrow - thymus Characteristics: mostly nucleus, very little cytoplasm Role: recognize antigens called T receptors |
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Central lymphoid tissue: thymus |
Primary site of B cell development |
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Peripheral lymphoid tissue: lymph nodes |
Sample antigens doe presence of foreign substance Trap and concentrate foreign substance |
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Peripheral lymphoid tissue: lymph nodes |
Sample antigens doe presence of foreign substance Trap and concentrate foreign substance |
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Peripheral lymphoid tissue: spleen |
White pulp: immune response takes place here Red pulp: contains large quantities of erythrocytes, macrophages and some lymphocytes Trap and concentrate foreign substances |
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High endothelial venues (HEV) |
- Lined with high cuboidal endothelial cells - lymphocytes contain homing receptors that interact with HEVs - organ specific molecules (addressins) expressed on endothelial cells and interact either homing receptors - this allows lymphocyte circulation |
