Intro To Adaptive Immunity Flashcards
What are the cell types in adaptive immunity?
B cells (secretes antibodies) and T cells (helper T cells and cytotoxic T cells which have different receptors)
What do B cells do?
Controls extracellular pathogens in peripheral tissues from hematopoietic stem cells -> lymphoid progenitor -> B-cell progenitor -> B cell
Has BCR (B-Cell RECEPTOR)
What do T cells do?
Control of intracellular pathogens
Helper T cells (Th cells) have cd4 molecule as receptor
Cytotoxic T cells (CTL) have cd8 molecule as receptor
Hematopoietic stem cell -> lymphoid progenitor -> T cell progenitor -> T helper cell or T cytotoxic cell (in thymus)
What is the different primary vs memory response?
Primary: first exposure to pathogens
Secondary/memory: subsequent exposure to same pathogen occurs larger and faster because memory b and T cells react at this response
What are the details of the primary immune response?
- Microorganism entry
- Establishment of infection
- Innate immune system starts inducing differentiation and clinal expansion from naive B and T cells
- Effector b and T cells control infection
- Effector B and T cells die through apoptosis
- Memory B and T cells remain in system for secondary response
What is the difference between effector and memory cells? How do they arise
Naive B/T cells differentiate into
Effector cells:
B cells -> plasma cells
helper T cells and cytotoxic t cells
Memory cells: remain after infection is resolved
What is the benefit of vaccination?
Primary immune response is skipped and adaptive response can work at real infection through immunological memory because more effector B and T cells produced
Memory of antibodies and cd8 and cd4 remain longer after infection
What are the primary and secondary lymphoid organs?
Primary: bone marrow and thymus (located above heart)
Secondary: lymph node
What is a general overview of what and where things occur in an immune response?
- Infection at barrier
- Innate immunity
- Lymphatic flow in to lymph node containing pathogen infected cell
- Lymphocyte development from bone marrow (B cell) and thymus (T cells) and movement through blood flow into lymph nOde
- Lymphocyte activation and different ion in lymph node to control pathogen
- Lymphatic flow out contains B and T cells to heart and out through blood
- B and T cells released to control other infected cells
What are the two types of lymphoid tissue? What occurs at each?
Primary lymphoid tissue: where lymphocytes are developed
- bone marrow (B cells and development of T cells)
- thymus (2nd development of T cells)
Secondary lymphoid tissue: where naive lymphocytes are further differentiated
- lymph nodes
- spleen
-mucosa-associated lymphatic tissue (MALT)
What is the lymphatic system?
network of tissues, vessels and organs that work in close proximity with the circulatory system
What is lymph?
interstitial tissue fluid that enters the lymphatic vessels to be transported by into the blood
What might the lymph carry?
pathogens or cellular waste and enter lymph nodes
- this is why surveils these entry points - lymph nodes and vessels
What is the connection between the lymphatic system and circulatory system?
- lymphatic capillaries run parallel to blood capillaries in all body tissues
- lymph leaves these tissues it carries waste products from tissues including dead cells, CO2, and pathogens
- lymph then passes and filters through lymph nodes
What is the significance of lymphatic vessels for injections?
injection into muscle where lymphatic vessel is to optimize immune response
(typically intramuscular on the arm where there is good blood flow)
injected vaccine components travel in the lymph to the nearest lymph nodes (arm pit)
How do T-cells develop?
- starts in bone marrow
- development continues in thymus lobule
- Double positive with both cd4 and CD8 receptors
- Differentiate into CD4+ (Th) and CD8+ (ctl) naive cells
What are the parts of a lymph node?
- artery vein (circulatory system)
- efferent & afferent lymphatic vessel (lymphatic system)
- germinal centre
- T cell zone
- B cell zone
T cells and B cells colocatized at the follicular border allowing for interaction
What is the purpose of mucosa-associated lymphoid tissue?
Site where B and T cells meet pathogens in mucosal area
Contains m cells (micro fold) which helps transport antigens into the tissue
Where is MALT found?
oral-pharyngeal cavity and gastrointestinal, respiratory, and urogenital tracts
(Tonsils, lungs, colon, appendix)
What is the role of the spleen?
Filters blood so blood flows in and out
shows B and T cell meeting blood-borne pathogens which is why immune system surveils here
Similar organization to to lymph nodes
How are tonsils protected by the immune system?
Mucosa tissue located for inhaled and ingested pathogens
Nasopharynx (monitors respiratory tract)
Oropharynx (monitor the gastrointestinal tract)
How are pathogens recognized?
Surface receptors:
T-cell receptors (TCR)
B cell receptors (BCR)
What do naive T cells and B cells do once developed from thymus and bone marrow?
Enters circulation and migrate to SLTs to look for pathogens
What do B cell receptors look like?
- variable region contains light and heavy region
- constant region is mainly heavy chain and some variable chain
- v shaped antigen binding site
- transmembrane region
- cytoplasmic tail
