W7- Lecture 31- Specific Immunity Flashcards
What do CD4 helper T cells help activate in the adaptive immune response ?
B cells (to turn into plasma cells ) that produce antibodies
CD8 cytotoxic T cells that lyse infected cells
Where are T cells matured ?
+ what selection do they under go
In the thymus
Both positive and negative selection
Where are b cells matured ?
Bone marrow
Only positive selection
What are the major difference between the production of B & T cells
B cells develop in the bone marrow constantly - mature in bone marrow
T cells the majority of them produced before puberty - mature in thymus
With maturity T cells develop distinct membrane bound membrane making two compounds callled
CD4+
CD8
Both T cells
Describe how T cells and B cells recognise foreign pathogens differently
Cytotoxic T cells - recognise proteins/ other long chain molecules (broader range of target pathogenic epitopes )
-protein antigens
B cells - recognise epitopes not whole proteins or long chains . More specific
-proteins, lipids carbs and nucleic acids
What is an antigen
Non-self molecular configuration
activate the adaptive response eg antibody production
What do lymphocytes recognise to produce an immune response?
Epitopes
What is Immunogenicity
an ability to induce a response mediated by the production of specific T cells or specific antibodies.
What is Reactivity in terms of immune responses
the ability to react with antibodies or specific T cells
What is a complete antigen vs partial antigen
Complete - has reactivity and immunogenicity
Partial- reactivity but lack Immunogenicity
After coming in contact with an immune cell when does an antigen go ?
Via blood to spleen
Or
Via lymph to lymph node
Where they are trapped by recticular fibres of the reticular cells
Or
in the case of the mucosal membrane, antigens are trapped by mucosa-associated lymphatic tissue (MALT).
What are major histocompatibility complex (MHC)
AKA human leukocyte action
Molecules (products of 12 alleles) that are expressed on the surface of cells that are important in immune responses
Guide T cells
Bind epitopes to antigens + present them to T cells
(identical to us )
Name the major difference between MGC class 1 & 2
Class 1- presents self proteins
Class 2 - foreign antigens presented
Where are are MHC aka HLA’s expressed
Every cell of the body except Red blood cells
Where are MHC 1 & 2 found
What do these receptors play n important roles in treatment
1- in plasma membrane of all body cells
2-on membranes of antigen presenting cells
E.g thymidine cells + active T cells
- important role in rejection of Donor tissue
What is the difference between where/ how B and T cells recognise antigens
B cells - recognise antigens in body fluids
T cells -only recognise antigens associated with MHC
Describe exogenous antigen processing (antigens found in body fluid )
Ingest antigen
Antigen digested into peptide fragments
Peptide fragments transferred to vesicle + MHC 2 molecule line inner membrane of vesicle
Vesicles fuse
Two components bind forming a complex
Vesicle undergo exocytosis
The MHC 2 attached to antigen fragments is presented on cell surface
After exogenous antigen processing where does the antigen presenting cell migrate to ?
+ purpose
Lymphatic tissue
to be presented to T cells
Describe endogenous antigen processing (antigens produced within cell)
Fragments associate with MHC 1
Forming complex
Complex moves to cell membrane where the antigen is displaced on the surface
Name the two steps of T cell activation
Co-stimulation
Helper T cell activation
Describe the co-stimulation of T cells
Cause
Name 1
happens when T cell binds with specific antigen on antigen presenting cell
Activation
Causing proliferation and differentiation
Cytokines e.gInterleukin 2
Where does the proliferation ans differentiation of T cells occur ?
Secondary lymphatic organs/ tissues
E.g tonsils
Describe the T cell activation by helpers T cell
Cd4+ cells normally develop into T helper cells
helper cells recognise MHC2/antigen complex
(if co-stimulated ) secrete cytokines e.h il 2
Triggering T cell proliferation
+ proliferation of B cells and NK cells
