Immune Responce To Infection Wrap Up Flashcards
What happens in bacteria make it past out first defences
Neutrophils enter the blood from bone marrow. Velcro like interactions between neutrophils and capillary wall. Inflammation makes capillaries leaky, allowing neutrophils to squeeze through walls and enter tissue. Neutrophils attracted to site of infections by chemicals released from damage/infected cells, or associated leukocytes (especially macrophages). Bacteria are phagocytosed, broken down by contents of phagolysosome.
What are the 2 types of mediated immunity that are involved in an adaptive response
Cell mediated immunity - phagocytes activate T cells. T cells find the pathogens and attack them through phagocytosis or the release of chemical toxins
Antibody mediated immunity - activated B cells give rise to antibody producing plasma cells - opsonisation, neutralisation, complement.
Outline the MHC1 ad MHC2 loading of dendritic cells
Viral proteins can enter both the phagolysosome and the cytosol of the DC
Phagolysosome antigen will be loaded onto MHC2 in the phagolysosome for T cell stimulation
Cytosol if antigen will be loaded onto MHC1 in Er/endomembrane system for CD8 T cell stimulation
How to cytotoxic T lymphocytes recognise virally infected cells
Interactions between MHC1 endogenous antigen presentation on virally infected cells, and TCR/CD8 co receptor on CTL
Outline the consequence of CTL-virally infected cell binding
Granules are released if CTL triggered appropriately by recognition of virus peptide in context of MHC.
Via the release of granzyme and perforin, cytotoxic T lymphocytes program virally infected cells to undergo apoptosis (in a controlled ordered manner as to prevent viral release into extracellular environment).
What is clonal selection
Selective expansion of lymphocytes that interact with antigen.
Only T cells stimulated by correct MHC/peptide complex will undergo clonal selection. This results in proliferation of T cells containing the favourable TCR for the given antigen.
Outline the process leading to the activation of B cells
Bacterial proteins enter the phagolysosome of DC.
Phagolysosomal antigen loaded onto MHC2 for CD4 helper T cell stimulation.
Helper T cells stimulate B cells to differentiate into antibody producing plasma cells (aswell as CD8 T cells to become cytotoxic) via the release of cytokines.
Only B cells that recognise antigen are activated.
What is antibody class (isotype) switching
During immune response, B cells can genetically switch the heavy chain to change class (isotype). This does not change the antibody specificity, but it does change the function
Outline the process by which memory B cells are produced
Activated B cells divide and differentiate int plasma cells that secrete antibody, as well as forming a seperate population of memory B cells.
Outline the characteristics of a secondary immune response in terms of B cells and antibody
At second encounter, memory B cells are more numerous and are rapidly stimulated by antigen to become plasma cells.
Secondary immune responses are characterised by the predominance of class switched antibodies (IgG, IgA, and IgE)
What cells does clonal selection apply for
B and T lymphocytes
Outline antibodies binding to defined regions of a larger structure
Antibodies bind to antibody binding diets of native antigens. Several different antibodies may target a single type of microbe
What is meant by the term native antigen
Native antigen means that the antigen has not been processed to peptide (or is not in the context of MHC)
What antibody isotypes are most present in primary, and secondary immune responses
Primary - IgM/IgD
Secondary - IgG > IgA > IgE = IgM = IgD
What are the 4 methods of vaccine used to mimic infection without exposing to danger.
Live attenuated (weakened from original disease causing germ). Live microbes that wont cause disease but will cause immunity.
Killed. Dead microbes.
Sub unit
Subunit mRNA (body has to produce protein from mRNA)
