Infection and immunity Flashcards
The ability of an organism to defend itself against infectious agents, foreign cells and proteins, and catastrophic cell dysfunction (e.g. cancer)
Immunity
Name the two different types of immunodeficiency
- Genetic inheritance (e.g. Severe Combined Immune Deficiency)
- Acquired during life (e.g. AIDS)
A damaging immune response by the body to a substance, especially a particular food, pollen, fur, or dust, to which it has become hypersensitive.
Allergy
Allergy and hypersensitivity result when the immune system responds….
innappopriately to antigens.
An extreme hypersensitivity reaction where the immune system attacks its own body tissues
Auto-immunity
In autoimmune conditions, what types of cells mount an attack against the body’s own tissues?
B & T cells. This is the result when T cell control mechanisms fail.
List the three key areas of immunological disease:
- Immunodeficiency
- Auto-immunity
- Allergy
Name the two branches of the immune system
Innate and adaptive
Which branch of the immune system is the first immunological mechanism for fighting against intruding pathogens?
The innate immune response
Which of the two branches of our immune system is more immediate (initiated within minutes or hours)?
Innate
Does the innate immune system have immunologic memory?
No
Which branch of the immune system is antigen dependent and antigen specific?
The adaptive immune response
Which of the two branches of the immune system has capacity for memory?
The adaptive immune response
What is the purpose of memory in the adaptive immune response?
Memory to specific antigens enables the host to mount a more rapid and efficient immune response upon subsequent exposure to the antigen. This should prevent an infection on the second encounter.
In which part of the lymphatic system do lymphocytes and macrophages generally reside (in concentrated areas)?
Lymph nodes
Where are blood cells produced, including B and T lymphocytes?
Red bone marrow
Which organ acts as an emergency blood store?
The spleen
Where is blood cleansed of pathogens and debris?
The spleen
What is the site of maturation of T-lymphocytes?
The thymus gland
What is the name of the inital cells that give rise to all other blood cells?
Hematopoietic stem cells
What is the “parent” cell of T cells, B cells, and natural killer cells?
Lymphoid progenitor
What is the “parent” cell of dendritic cells, granulocyte-monocyte progenitors, eosinophil progenitors, basophil progenitors, erythroid progenitors, and megakaryocytes?
Myeloid progenitor
What is the job of dendritic cells?
Antigen-presenting cells
Megakaryocytes produce what kinds of cells?
Platelets
Erythroid progenitors produce what kind of cells?
Erythrocytes (red blood cells)
Which type of cell is mostly involved with host defenses against multicullular parasites?
Basophils
What type of cell is mostly involved in defense against nematodes and parasites?
Eosinophils
This type of cell coordinates the inflammatory response and is the 1st line of defense in bacterial infections
Neutrophils
These are the “scavenger” cells; phagocytic, highly migratory. Also professional antigen presentation
Macrophages
Macrophages are produced from…
Monocytes
Name the leucocytes with myeloid lineage (4)
- Basophils
- Eosinophils
- Neutrophils
- Monocytes/macrophages
Name the leucocytes with lymphoid lineage (4)
- T cells (CD8 and CD4)
- B cells
- NK cells
- Dendritic cells
What would trigger a haematopoietic stem cell to differentiate into either a myeloid progenitor cell or a lymphoid progenitor cell?
Molecular messengers such as cytokines and chemokines
Name the two different types of T cells
- T Helper cells (CD4+)
2. Cytotoxic cells (CD8+)
What type of lymphocyte produces antibodies?
B cells (plasma cells)
True or false: dendritic cells can come from either myeloid or lymphoid progenitor cells
True
These are the effector lymphocytes of the innate immune system. They are best known for killing virally infected cells, as well as for detecting and controlling early signs of cancer.
Natural killer cell
Natural killer cells are derived from what type of progenitor cell?
Lymphoid progenitor
This type of leucocyte activates B cells to secrete antibodies and macrophages. It can also activate cytotoxic T cells
T helper cell (CD4+)
This type of T cell directly kills virally infected cells and tumours
T cytotoxic cell (CD8+)
Which leucocyte is integral to the adaptive immune response?
B cells
Define “immunological memory”
The adaptive immune system exhibits a memory function that kicks in quickly if a pathogen is encountered again later on in life. It acts quickly on the second exposure, providing a robust response that ideally should prevent an infection.
This is the state of immunological non-reactivity to an antigen
Tolerance
What type of immune disorders can result from a breakdown of tolerance?
Auto-immunity or allergies
Describe how alleriges can develop
Allergies can result when there is a breakdown of tolerance, and the body reacts to potential antigens that are not actually harmful (e.g. pollen, dust).
Describe how auto-immunity can develop
Auto-immunity can result when there is a breakdown of tolerance, and the body reacts to its own tissues as if they were antigens.
What are the steps involved in antigen-antibody phagocytosis?
- Antibodies (produced by B cells) bind to specific antigens on pathogens
- Antibodies then act as a bridge between a phagocytic cell and a pathogen
- The antigen-mediated cross-linking drags Fc receptor complexes on the phagocytic cell closer together, stimulating phosphorylation to occur
- The phosphorylation results in signal transduction, which signals the phagocytic cell to engulph the pathogen
What triggers phagocytosis of a pathogen?
The Fc receptors being dragged closer together by cross-linking
Glycoproteins that have the ability to bind to a specific antigen are called
antibodies
What is a naive B cell?
A B cell that has not been exposed to an antigen
What happens to a B cell when it is exposed to an antigen?
The cell becomes either a memory B cell or a plasma cell that secretes antibodies
What is the result of a B cell receptor becoming activated by antigen cross-linking, and cytokine stimulation by T helper cells?
The membrane-bound surface antibody on a B cell promotes production of the soluble form of antibodies
What type of bonds join the light and heavy chains of an antibody?
Disulphide bonds
The grouping of different antibodies based on function
Antibody isotype
Name the 5 antibody isotypes
- IgM
- IgG
- IgA
- IgE
- IgD
Which is the most abundant internal immunoglobulin?
IgG
Which immunoglobulin protects external surfaces?
IgA
Which immunoglobulin is most efficient against bacteria?
IgM