Basic Science Flashcards
Name the myeloid cells
- Neutrophils
- Eosinophils
- Basophils
- Monocytes (macrophages)
Name the lymphoid cells
- B (differentiate into plasma cells)
- T
- Natural killers
Function of plasma cells
Make and secrete antibodies
What are dendritic cells
Cells that are like macrophages (but are extensions of the plasma membrane). Process antigens and present it to the T cells. Messenger between innate and adaptive
Function of the dendritic cells
Phagocytosis in areas where internal and external environments meet (GI tract). Can also activate T-cells in secondary lymphoid organs.
What are mast cells derived from
Differentiation of unique bone marrow cells that have exited blood vessels to enter CT. They differentiate in the CT.
Where are mature mast cells NOT found
In the blood, because they must leave the blood and enter the CT in order to mature
What do mast cells secrete
Histamine
What cells play a role in adaptive immunity
B/T lymphocytes
Overall function of the myeloid cells (neutrophils, baso, etc)
Secrete inflammatory mediators and aid in phagocytosis
Where are the myeloid cells developed
Bone marrow
Where do B cells and NK cells mature
Bone marrow
Where do T cells mature
Thymus
Where are lymphocytes activated
Peripheral lymphoid organs
What is the function of neutrophils
- Release chemicals involved in inflammation
2. Phagocytosis
What is the function of Basophils
similar to mast cells. Release histamine and chemicals involved in inflammation
Function of Eosinophils
- Destroy parasites
2. Aid in immediate hypersensitivity reactions
Function of Monocytes
Phagocytosis when they become macrophages in tissue
How do B cells work (function)
- Initiate antibody immune response by binding to specific antigens (immunoglobulins, ex IgE)
- Once activated, they transform into plasma cells, which secrete antibodies
- Present antigent to helper T cells
Function of cytotoxic T cells
Bind to antigens on plasma membrane of target and destroy the cell
Function of helper T cells
Secrete cytokines that help activate B cells, NK cells, and macrophages
Function of NK cells
Bind directly to virus/cancer cells and kills them
Functions of macrophages
- Phagocytosis
- Process and present antigens to helper T cells
- Secrete cytokines
Which cells are responsible for innate immunity
- Neutrophils
- Basophils
- Eosinophils
- Monocytes
- NK
How does the innate immunity system work
Recognizes carbs or lipids on an invading organism but does not need to recognize a specific antigen (pathogen they recognize is called a PAMP - pathogen associated molecular pattern)
Steps of inflammation
- Bacteria are introduced
- Chemical mediators (cytokines) cause vasodilation and recruit neutrophils
- Neutrophils enter tissue and eat bacteria (causes edema)
How does the adaptive immunity system work
Lymphocytes must recognize a specific foreign material by binding to an antigen.
How does lymphocyte activation occur
The binding an antigen to a receptor
What is clonal expansion
When a lymphocyte binds to an antigen it becomes active and undergoes multiple rounds of cell division. This means that many daughter lymphocytes develop from one progenitor and are identical in their ability to recognize a specific antigen
How do T and B cells develop large number of receptors
Via clonal expansion (some cells will carry out attack responses while others become memory cells).
How do plasma cells work
They send out antibodies that opsonize the foreign bacteria, which then are targeted by the innate system (neutrophils, basophils, etc)
What are the secondary lymphoid organs
- Lymph nodes
- Spleen
- Tonsils
- Lymphocyte accumulation in GI respiratory, genital, and urinary tracts (mucosal linings)
What are the primary lymphoid organs
Bone marrow and thymus
What types of lymphocytes are in the primary lymphoid organs
Mature, but naive cells. They become activated once in the blood stream or in secondary lymphoid tissue
Macrophages of the spleen are responsible for what
Eating old or used red blood cells
How does most of the “trafficking” of lymphocytes occur
Lymphocytes leave the secondary lymphoid organs and enter the lymphatic vessels which are carried into the blood and then back into lymph nodes. Recirculation process that allows for a lymphocyte to encounter its specific antigen.
What is unique about NK cells
They arise from bone marrow but unlike B and T cells they are not specific to a given antigen
Humoral responses (B cell)
Are antibody mediated responses. Meaning they are activated by a chemical mediator (i.e. cytokine)
Cell mediated (T-cell)
Responses that are regulated by cells (cytotoxic and helper T cells)
What are B cell plasma antibodies called
Immunoglobulins
What are immunoglobulins made of
4 interlinked polypeptide chains
2 heavy, 2 light chains
What are the 5 classes of immunoglobulins
A, D, E, G, and M (these are determined by their chain sequence)
Why are NK cells considered a part of adaptive immunity
Because their function is greatly enhanced by antibodies or cytokines that are secreted by helper T cells
Immune tolerance
Lack of an immune responsiveness to self. The body knows not to attack itself based on 2 mechanisms: Clonal deletion and clonal inactivation. (body learns this over time)
Atopy
A tendency to be hyper allergic. Typically presents as atopic dermatitis, allergic rhinitis, or asthma
Active immunity
Immunity or resistance that is built up as a result of contact with an organism. Antibodies are produced as a direct reaction to the antigen.
Passive immunity
Transfer of active or ready made antibodies from one individual to another. Usually occurs as a transfer from mom to baby via the placenta.
Which classes of immunoglobulin is the most abundant and name their function
- IgG (gamma globulin) and IgM - fight against bacteria and viruses in EC fluid and serum.
- IgG is the only one that can cross the placenta
- IgM is the 1st antibody made after B-cell activation
What is the function of the IgE immunoglobulins
Defense against parasites and mediate (or cause trouble) allergic responses
What is the function of the IgA immunoglobulins
Secreted in the linings of the GI, resp., urinary tracts and act locally at these surfaces. Also secreted in mammary glands and are the major antibodies in milk.
Opsonization
The antibodies coat the bacteria which then allows for phagocytosis from other cells (marks the cell as a target).
Neutralization
Antibodies bind to an antigen which then deactivates or prevents the foreign object from doing its thing (only uses the “hands” of the antibody). Good for fighting viruses
Complement activation
IgG and IgM help active the complement system which helps innate cells kill antigens more easily. The presence of the antibodies makes the cell “leaky” (MAC) which allows for phagocytosis.
3 results of complement - opsonization, cytolysis, inflammation
How do vaccines work
Small quantity of living or dead pathogen is injected which creates an active immune response. The body builds up antibodies.
Steps or course of an antibody response
- Bacteria enters blood or lymphatic vessel
- Bacterial antigen binds to a specific receptor on plasma membrane of B cell (activation) - will make a small amount of IgM initially
- B cell differentiates into plasma cells or memory B cells
- Plasma cells secrete antibody (usually IgG)
- Antibody circulates all over body via the blood
- Antibody binds with antigen on the surface of bacteria
What is a Type I hypersensitivity (allergy)
Immediate. Anaphylactic reactions that are IgE mediated. IgE binds to mast cells or basophil which then release a large amount of histamine
What is a Type II hypersensitivity
Cytotoxic hypersensitivity. IgG/IgM mediated. These antibodies (bound to antigen in tissue) lead to damage or destruction of cells in tissue and is often seen in hemolytic diseases.
What is a Type III hypersensitivity
Immune-complex hypersensitivity. Too much antigen-antibody complex formation. These complexes activate the complement system which induces an excessive inflammatory response (within solution). Often occurs in vessel walls and kidneys.
What is a Type IV hypersensitivity
Delayed hypersensitivity. Independent of antibodies. Mediated by an increased secretion of cytokines by helper T cells (activates macrophages)
Symptoms of Type I (IgE mediated)
- hay fever - congestion, runny nose, sneezing, difficulty breathing (increased blood flow, swelling of epithelial lining and smooth muscle contraction
- Anaphylaxis - Severe hypotension and bronchiolar constriction
- Atopy - dermatitis, asthma, allergic rhinitis
Examples of pathology caused by Type II hypersensitivity
- Hemolytic anemia
- Thrombocytopenia
- Graves disease
Examples of pathology caused by Type III hypersensitivity
- Poststreptococcal glomerulonephritis (PSGN)
- Serum sickness
- Autoimmune disease - lupus
Attenuated vaccine (live)
Vaccine that has a reduced virulence load but is still alive
Inactivated vaccine
Vaccine that has bacterial/viral particles that were grown in culture and then killed.
Conjugate vaccine (subunit/polysaccharide)
Vaccine that is made by covalently attaching a polysaccharide antigen to a carrier protein which then confers the immune attributes of the carrier to the attached antigen
Toxoid vaccine (inactivated toxin)
Vaccine that contains a harmless toxoid (i.e. endotoxins of bacteria) and learns how to fight off the natural toxin. Ex: tetanus and diptheria
