Introduction to specific immunity Flashcards
What does Immune response mostly rely on?
B and T cells
Where do B cells develop?
Within Bone marrow
Where do T cells develop?
Pre-t cells that migrate into thymus from bone marrow
With maturity what do T and B cells develop?
distinctive membrane bound proteins include antigen receptors and CD4 and CD8 proteins
What are the 2 types of immune responses?
Cell mediated
Antibody mediated immunity
What is Cell mediated immunity?
involve CD8 t cells proliferation into cytotoxic t cells
What is CMI largely associated with?
Targeting intracellular pathogens and some cancer cells
What does Antibody mediated immunity involve?
Transform B cells into plasma cells, Plasma cells synthesize and secrete immunoglobulins and bind to inactive specific antigens
What is AMI associated with?
targeting antigents in body fluids and pathogens that replicate - aided by CD4 helper cells
What are antigens?
Single foreign proteins that is part of a large complex, it activates adaptive response and whole ones cant be detected
What is Immunogenicity?
Ability to induce a response mediated by production of specific T cells or specific antibodies
What is reactivity?
Ability to react with antibodies or specific T cells
What do T cells respond to?
Only protein antigents
Where do B cells respond to?
Proteins, lipids,carbohydrates and nucleic acids
What are epitopes?
Small component of antigens that initiate immune response
How are antigens trapped in the mucosal membrane?
Trapped by mucosa-associate lymph tissue (MALT)
What does MHC do?
Guide recognition of antigen by T cells, bind epitopes of antigents and highly polymorphic
What are MHC also known as?
HLA
How are MHC expressed in the body?
By every cell except RBC
How do MHC function?
Help T cells recognise foreign antigens
What are the 2 types of MHC?
Class I and Class II
What are MHC I?
built into PM of all bodies cells
What are MHC II?
Found on membrane of antigen presenting cells such as active T cells
What do MHC play a part in?
Rejection of donor tissue
What can B cells recognise?
Antigens in body fluid
What do T cells recognise?
Antigents presented in combo with MHC
Where do MHC arise from?
Fragments of self protein associated with peptide binding groove or new MHC
What are the 2 ways processing of foreign antigens can occur?
Exogenous antigen
Endogenous antigen
What is Exogenous antigen processing?
Antigents found in body fluids, dealth by antigent presenting cells APC.
What do APC include?
Macrophages, B cells and Dendritic cells
What do APC ingest?
Antigen then antigen ingested into peptide fragments transferred to small vesicles
What does APC synthesis?
MHC II molecules as packed into inner membrane of vesicles
What process does Large vesicles with MHC II undergo?
Exocytosis
What is Endogenous Antigen processing?
Antigens produced within a cell and associate with MHC I molecules - moves to cell membrane as surface antigen
What do T cells not recognise?
Free antigens and as only directed to infected cell
What is the 2 stage process of T cell activation?
Initial binding of t cell with specific antigen
What is co-stimulation?
More than 20 known co-stimulants include cytokines and pairs of PM molecules
How does co-stimulation function?
Allows two cells to temporarily attach to knoe another
What does lack of co-stimulation result in?
Anergy
Where does the process of proliferation and differentiation of T cells occur?
In secondary lymphatic organs and tissues
What are the 3 main types of T cells?
Helper t cells
Cytotoxic t cells
Memory cells
What do Helper cells do?
Express the CD4 membrain protein into TH cells
What do TH cells do?
Recognise MHC II complexes and if costimulated secrete range of cytokines
What does the cytokine IL-2 do?
Functions by triggering T cell proliferation and function for TH cells
What do Cytokines do?
Enhance immunocompetent cell function
What are cytokinees?
Small hormones that stimulate or inhibit cellular differentiation
What are the most common Cytokines?
Interleukins 1-5 , tumour necrosis factor, TGF-B, Gammar IFN, A+B IFN
How does Cytokine treat medical conditions?
Cytokine therapy
Where are Cytotoxic cells derived from?
CD8 cells
What cells reconigse MHC I on virus cells?
TC cells (cytotoxic t)
How are Cytokines secreted?
As a result of Helper cell secretion, only once encountered same antigen
How do TC cells destroy target cells?
Secreting porforin
Secreting Lymphotoxin
What are Memory cells?
T cells remain after infection give rise to these
How are memory cells maintained?
Allow rapid response to reinvasion by initial antigenic material
What does T cell Maturation occur?
Rearrangements of germ line TCR genes
What are developing t cells in thymus known as?
Thymocytes
What do thymocytes do?
Proliferate and differentiate into sub-populations of mature t cells
What is positive selection?
MHC restriction
What is Negative selection?
Deletion of autoreactive cells
