Adaptive Immunity - B and T cells Flashcards
What type of immunity is specific, requires prior exposure to foreign substances and creates immunological memory?
Adaptive immunity
What are the adaptive immune responses? (3)
- Recognition of antigen
- Activation of lymphocytes (B and T cells)
- Attack against antigen and creation of memory
What type of stem cell divides to produce B and T cells?
Haematopoietic stem cell (HSC)
Where do B and T cells develop?
Bone marrow
Where do mature B cells move to?
Periphery (lymphoid organs)
Where do T cells migrate to?
Thymus
What immunoglobin do immature B cells have as a receptor on their surface? (known as BCR/B cell receptor)
IgM molecule (unique)
What is the purpose of the BCR on B cells?
To recognise antigens
What is immunoglobin (Ig)
An antibody
What is the structure of Ig (antibody)
4 interliked polypeptide = 2 long heavy chains, 2 short light chains
What are the 5 classes of immunoglobins?
IgM, IgG, IgE, IgA, and IgD
What are the 2 most abundant immunoglobins in mammals?
IgM and IgG
Which immunoglobin participates in defences against multicellular parasites and allergic responses?
IgE
What immunoglobin is secreted by plasma cells in the linings of gastrointestinal, respiratory, and genitourinary tracts to protect locally?
IgA (dimer)
What is a major antibody in milk?
IgA (dimer)
What immunoglobin’s function is unclear?
IgD
What is the binding site of the antibody known as?
Epitope
A substance capable of stimulating an immune response is known as what?
Antigen
What is the difference between humoral and cellular immunity?
Humoral is activated by B cells, and cellular is activated by T cells
The BCR is activated by antigens and by Helper-T cell cytokines is known as what?
T-dependent activation
T-dependent activation
B cells proliferate into plasma cells that make antibodies, some form into memory cells
Are lymphocytes specific or non-specific for antigens?
Specific for just one type of antigen
Upon binding the antigen, lymphocyte undergoes cell division to make what?
Clones
What do clones function as?
Plasma cells - carrying out attack on antigen
Memory cells - for future encounters with that antigen
What do activated B cells differentiate into?
Plasma cells
Any T cells which receive too little or too much of a signal are deleted (apoptosis) describes what?
Clonal deletion
In the selection of T cells, what happens to T cells with strong affinity?
They are deleted
What are useful T cells differentiated into?
CD4+ ‘helper’ T cell
CD8+ ‘killer’ T cell
What do T cells recognise?
Antigens
How are antigens recognised?
Major Histocompatibility Complex (MHC)
What are the 2 forms of MHC?
MHC-I = CD8+ T cells
MHC-II = CD4+ T cells
Where are MHC-I molecules expressed?
On all mammalian cells
Where are MHC-II molecules expressed?
Selectively expressed on professional antigen-presenting cells
What cells are very good at presenting antigen via MHC-I and MHC-II?
Dendritic cells
If antigens are engulfed from outside the cell and destroyed (bacteria), they are presented to…?
MHC-II (CD4+ T cells)
If antigens are presented from inside the cell they are presented to…?
MHC-I (CD8+ T cells)
What do activated T-cells proliferate rapidly and differentiate into?
Functional effector T cells
What does Th1 secrete?
IFNy and activates macrophage function
What does Th2 secrete?
IL-4 and ‘helps’ antibody function
