Cell mediated immunity Flashcards
(26 cards)
T-cells are selected in the thymus based on what two factors?
If they’re able to see MHC
If they’re able to see self
What is MHC? What are the 2 classes?
Major histocompatibility complex (glycoprotein) Class I or class II
Which cells express MHC class I on their surface?
All nucleated cells
Execptions: RBCs, platelets and nerve cells
Which cells express MHC class II on their surface?
Antigen presenting cells (APCs)
What are the functions of MHC class I and II?
Transport samples (peptides) of intracellular proteins to cell surface T cells constantly inspect surface of cells
Where are self proteins expressed? Which cells are they on?
Expressed on cell surface, within groove of MHC
All nucleated cells
Do circulating T-cells respond to self peptides on MHC-1?
No - only respond if abnormal peptide expressed on surface
What is meant by the MHC or genetic restriction of the immune response?
T-cells can only respond to antigens if they are presented in MHC molecule
What cell receptors bind to MHC?
T cell receptors
B cell receptors
(CD4 and CD8 can also bind)
Which cells are antigen presenting cells (APCs)?
Dendritic cells
Macrophages
B-cells
Basophils
Immunity can be naive or primed. Where do these different immune statuses start their response?
Naive - lymph nodes, at draining site of antigen exposure
Primed - local site of antigen exposure
What lymphoid tissues are involved with naive or primed immune response?
Naive - lymph nodes and spleen
Primed - MALT
How does naive or primed status affect immune response time?
Naive - slow >3 days
Prime - fast 1-2 days
What are the 2 routes of antigen entry into cells? Are these MHC class I or II restricted? (route of entry dictates what type of antigen processing and presentation)
Phagocytosis/endocytosis - MHC class II restricted Direct entry to cytosol - MHC class I restricted
What are the 2 types of antigen processing? What causes these?
Endogenous - caused by antigen entering cell via phagocytosis/endocytosis
Exogenous - caused by antigen directly entering into cytosol
Exogenous antigen processing involves the MHC class II pathway. Which cell recognises the antigens? What do they cause to be secreted?
CD4+ T helper lymphocytes (T cell receptor on this)
Cytokines
Endogenous antigen processing involves MHC class I pathway. Which cell recognises the antigens? What do they cause to be secreted?
CD8+ T cytotoxic lymphocytes
Cytokines
Antigen processing can be endogenous or exogenous. What type of pathogens does each respond to?
Endogenous - intracellular pathogens e.g. viruses
Exogenous - extracellular pathogens e.g. bacteria
Where do B cells mature? Where do T cells mature?
B - bone marrow or bursa of fabricus (birds)
T- thymus
What cell produces plasma cells?
B cells
What cell produces CD4+ and CD8+?
T cells
What are the 2 kinds of infections according to the immune system? What lymphocytes function in each?
Intracellular infection - cytotoxic T cells
Extracellular infection - B cells, secrete antibodies
Infections can be extracellular or intracellular. Do B cells or T cells work inside or outside of a cell?
B cells - outside a cell, produce antibodies to bind to pathogen
Cytotoxic T cells - inside a cell
Why can’t antibodies function during intracellular infections?
Antibodies cannot penetrate cell membrane
