Immune Response Mechanisms

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Questions and Answers

What is the function of Helper T cells (CD4) in the immune system?

To produce antibodies against pathogens

To release cytokines and activate other immune cells (correct)

To inhibit immune responses and prevent autoimmune diseases

To recognise and eliminate infected body cells

What type of hypersensitivity occurs within seconds to 20 minutes?

Autoimmune response

Immediate hypersensitivity (correct)

Innate immune response

Delayed hypersensitivity

What is the function of Regulatory T cells (CD 4-25) in the immune system?

To activate immune responses against pathogens

To produce antibodies against infected cells

To eliminate infected body cells

To inhibit immune responses and prevent autoimmune diseases (correct)

What type of cells do Helper T cells (CD4) activate?

B cells and cytotoxic cells Signup and view all the answers

What do Mast cells release in immediate hypersensitivity reactions?

Histamine Signup and view all the answers

What is the function of cytotoxic cells in the immune system?

To recognise and eliminate infected body cells Signup and view all the answers

What is the function of neutrophils in the immune system?

Engulf and destroy bacteria, and clean up debris Signup and view all the answers

What is the main function of the spleen in the immune system?

Filtering of the blood and removal of worn-out cells Signup and view all the answers

What is the difference between innate and adaptive immunity?

Innate immunity is non-specific, while adaptive immunity is specific Signup and view all the answers

What is the function of lymph nodes in the immune system?

Filtering of lymph and trapping of pathogens Signup and view all the answers

What is the role of interferon in the immune system?

Interference with viral replication Signup and view all the answers

What is the function of basophils in the immune system?

Production of histamine and heparin Signup and view all the answers

What is the main function of the thymus in the immune system?

Maturation of T-lymphocytes Signup and view all the answers

What is the primary function of the immune system?

To defend against disease and tissue damage Signup and view all the answers

What is a characteristic of the adaptive immune system?

It has memory Signup and view all the answers

Which type of lymphocyte recognizes free pathogens such as bacteria, toxins, and viruses?

B-lymphocytes Signup and view all the answers

What is the function of T-lymphocytes in the immune response?

To recognize infected or cancerous body cells and activate cell-mediated immunity Signup and view all the answers

What is the term for cells that display a unique type of receptor that responds to a distinct antigen?

Immunocompetent Signup and view all the answers

What is the function of antibodies in the immune response?

To recognize specific antigens and neutralize them Signup and view all the answers

What is the term for the process by which B-cells differentiate into plasma cells and memory cells?

Differentiation Signup and view all the answers

What is the function of plasma cells in the immune response?

To produce specific antibodies against a particular pathogen Signup and view all the answers

What is the term for the proteins produced by B-cells that recognize specific antigens?

Antibodies Signup and view all the answers

What is the name of the receptor found on the surface of B-cells that recognizes specific antigens?

B-cell receptor Signup and view all the answers

What is the approximate number of lymphocytes in the human body?

2 trillion Signup and view all the answers

Study Notes

Immune System

The immune system helps to guard against disease and tissue damage
Immune cells are distributed throughout the body, but are highly concentrated in blood and lymphatic tissue

Functions of the Immune System

Defense: against invading microorganisms
Clean up: removes damaged tissue
Surveillance: identifies and destroys abnormal body cells

Lymphoid Tissue

Bone Marrow: site of white blood cell production
Lymphatic Vessels: carry lymph from tissues to lymph nodes and lymph organs before returning to blood
Lymph Nodes, Tonsils, MALT, appendix: collections of lymphocytes for immune response and macrophages to remove debris
Spleen: replaces worn out blood cells, collections of lymphocytes for immune response and macrophages to remove debris
Thymus: site of T-lymphocyte (T-cell) maturation

White Blood Cells

White Blood Cells (leukocytes) make up less than 1% of total blood volume
General Functions: major cells of the immune system, internal defense against foreign cells, remove debris, destroy cancer cells
5 Types: Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils

Leukocyte Type and Appearance

Granular leukocytes take up certain dyes to look grainy under the microscope
Agranular leukocytes appear smooth
The shape of the nucleus and the size of the cells are also characteristic

Functions of WBCs

Neutrophils: phagocytic, engulf and destroy bacteria, clean up debris
Lymphocytes:
- B-cells: produce antibodies against foreign cells or viruses
- T-cells: kill infected cells, cancerous cells
Monocytes: phagocytic, clean up debris, foreign material
Eosinophils:
- allergic reactions
- attach to and kill parasites
Basophils:
- Histamine: allergic response
- Heparin: fat removal, prevent clotting

Infected Body Cells

Can be infected by:
- Virus
- Mutated cancer cells
- Transplanted donor cells
Killed by:
- Lysis
- Granzymes that induce apoptosis

Helper T Cells (CD4)

Recognize APC MHC II antigen presenting cells
Release cytokines, chemicals that are necessary to activate other immune cells
Activate:
- B cells
- Cytotoxic cells
- Attract neutrophils and macrophages

Regulatory T Cells (CD4-25)

Inhibit innate and adaptive immune responses to keep the system in check
Under research for autoimmune disease control

Hypersensitivity

Abnormal, vigorous immune responses (overzealous immune system)
Immediate hypersensitivity: occurs within seconds to 20 minutes
Allergies and Asthma:
- Plasma cells produce IgE antibodies which attach to Mast cells
- Mast cells release histamine, which causes inflammation and itching
- Also releases non-specific immunity

Adaptive Immune System

Antigen-specific: requires the production of specific lymphocytes and antibodies against a specific antigen
Systemic: not restricted to the initial infection site
Has memory: second encounter causes a more rapid and vigorous response

B-cells and T-cells

Adaptive immune responses are mediated by B cells and T cells
B-lymphocytes (B-Cells):
- Born and mature in the Bone Marrow
- Housed in lymphoid tissues
- Recognize free pathogens (bacteria, toxins, viruses)
- Involved in Antibody-mediated Immunity
T-lymphocytes (T-cells):
- Born in Bone Marrow, mature in thymus
- Housed in lymphoid tissues
- Recognize infected or cancerous body cells
- Involved in Cell-Mediated Immunity
- Involved in activating total, combined immune responses

Immunocompetent B or T cells

Immunocompetent: cells display a unique type of receptor that responds to a distinct antigen
Become immunocompetent before they encounter antigens they may later attack
Are exported to secondary lymphoid tissue where encounters with antigens occur
Mature into fully functional antigen-activated cells upon binding with their recognized antigen

Antigens

Any molecule or partial molecule that triggers an immune response
Examples: cell proteins, carbohydrates, lipids that are part of bacterial cell structure, bacterial released toxins
B-cells and T-cells have specific receptors for specific antigens
2 trillion lymphocytes in the body, each lymphocyte can only recognize ONE out of 100 million possible types of antigen

B-Cells

Pathogen invades the body
Specific B-Cell with pathogen receptor recognizes specific pathogen
Specific B-Cell differentiates into:
- Plasma Cells: produce specific antibodies for that pathogen
- Memory Cells: store memory of antigens to produce antibodies upon later infection, lay dormant until the 2nd infection by the same pathogen

Antibodies

Also called immunoglobulins
Y-shaped proteins that recognize specific antigens
5 types:
- IgM: stays on B cell to act as BCR for antigen
- IgG: MOST COMMON, secreted to respond to most antigens
- IgE: secreted to respond to parasitic worms, allergic responses
- IgA: secreted mostly in mucous membranes
- IgD: stays on B cell, function unknown

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Description

This quiz covers the mechanisms of immune response, including the recognition of infected cells, activation of immune cells, and the release of cytokines. It also touches on the role of helper T cells and antigen presentation.