Adaptive Immunity: B Cells and Immunoglobulins Flashcards
T cells protect our body against…
- Cancer cells
- Infected cells by pathogens
What do B cells produce to fight against antigens?
Antibodies
How do B cells divide?
Clonal expansion
B cells are also…
Antigen presenting cells
Swollen lymph nodes are caused by…
- B or T cells dividing and making more of themselves so they can fight the infection
- Clonal expansion
Who does the work in cell mediated immunity?
T cells
What do T cells fight against during cell mediated immunity?
- Fungi
- Parasites
- Intracellular bacteria
- Most viruses
- Cancer cells
- Surgically transplanted or transfused foreign tissues
Who does the work in humoral immunity?
B cells
Humoral immunity
Antibodies produced can recognize virtually any antigen and can fight infections through several mechanisms
What does humoral immunity fight against?
Extracellular organisms, some parasites, some viruses
Passive immunity
Immunity passed from mother to fetus
Primary source of B cell maturity occur where in fetuses?
Liver
Passive immunity uses what type of immunoglobulins?
IgG
Types of B cells
- Transitional b cells
- Naive b cells
- Memory b cells
- Plasma b cells
What are transitional B cells?
- Link between immature and mature B cells
- Travel between bone marrow and secondary lymphoid tissues
Autoantibodies
Antibodies that attack the host
Naive B cells
After B cell matures, remain naive till activated
When are naive B cells activated?
When a mature b cell is exposed to its specific antigen
Memory B cells
- Remain in bloodstream after infection subsides
- Quickly activates with help of T cells if you are reexposed to same pathogen
Plasma B cells
- Produces antigen specific antibodies
- Respond to chemical signals secreted by T cells during an infection
Antigen presenting cells
- B cells
- Macrophages
- Dendritic cells
Antibody-mediated immunity (humoral)
B cells use antibodies to tag pathogens for destruction
Steps to antibody-mediated immunity (humoral)
- 1: Cell triggered when its receptor matches pathogen antigen
- 2: B cell divides into antibody secreting cells/plasma cells and memory cells
- 3: Plasma cells tag pathogens for removal and memory cells hibernate for next time
What uses cross linking?
B cells
What do B cells recognize on pathogens?
Antigens with multiple and repetitive epitopes
T cell independent B cell activation difficulties
- Difficult for clustering B cells to bind and requires T cells to help
- Most antigens are made from proteins and they are not repeating
Is T cell independent or dependent B cell activation more common?
T cell dependent is more common
T cell dependent B cell activation
Protein antigens cannot crosslink multiple B cell receptors
3 signal process for T cell dependent activation?
- 1: Antigen recognition and binding by B cell
- 2: Derived from B and T cell interactions
- 3: Cytokines released by the help T cell stimulate B cell
CD40-CD40L interactions importance
Amplifies immune response and production of antibodies
IgM
- First antibody produced
- Produced when we were born
- Activates complement system
IgA
Body secretions, newborns acquire from breastmilk
IgE
- Act as antigen receptor
- Releases histamine
What immunoglobulin is present in basophils and mast cells?
IgE
What immunoglobulin is associated with allergic reactions?
IgE
IgD
Monomer, don’t know much about
IgG
- Involved in opsonization
- Can GO past placenta and give newborns passive immunity
- As the baby is coming out
- Helps complement system
What is the most abundant immunoglobulin?
IgG
What are antibodies?
Proteins that tag antigens for destruction
How many antigens can a B cell bind to at one time?
2
How many antigens can a T cell bind to at one time?
1
What can B cell receptors interact with?
- Wide array of molecules
- Proteins, lipids, nucleic acids, and carbohydrates
Epitopes
- On antigen
- Key that will go in the lock of B cell
What do T cell receptors recognize? Why?
Protein antigens on MHC because they only have one binding site
Auto reactive B cells
Produce antibodies against our own cells which cause autoimmunity
Plasma cell definition
B lymphocytes that are responsible for the production of large amounts of antibodies
Memory cell definition
B cells that are responsible for immunological memory and creating secondary immune responses
Plasma cell main function
Make lots of specific antibodies
Memory cell function
Remember antigens and act when exposed a second time to antigen
Plasma cell size
Enlarged cells
Memory cell size
Small cells
Plasma cell lifespan
A couple days to months, comparatively short
Memory cell lifespan
Long lived
Active humoral imminity
Infection or vaccines
Passive humoral immunity
The body doesn’t have to recognize an antigen and generate antibodies
Passive humoral immunity examples?
- IgG passed from mother to child
- IgA through breast milk
What are the two major lymphocytes involved in adaptive immunity?
T cells and B cells
What are the two types of adaptive immune responses?
Cell-mediated immunity and humoral immunity
What is T cell independent B cell activation?
T cell independent activation occurs when B cells recognize antigens with multiple and repetitive epitopes without T cell help
