Year 12- Immunology Flashcards
Describe phagocytosis
- Engulf pathogen by endocytosis
- Forming vesicle/phagosome which fuses with lysosome
- lysosomes contain hydrolytic enzymes (lysozymes) that hydrolyse molecules of pathogen OR digests pathogen.
- antigens are displayed on cell membrane
Note: waste material is also removed by exocytosis
Describe how vaccination leads to production of antibodies and immunological memory
- Vaccine contains antigen from pathogen.
- phagocyte engulfs and presents antigen on its surface.
- T helper lymphocyte with complementary receptor protein binds to antigen.
- T helper lymphocyte releases cytokines to stimulate specific B lymphocyte to divide by mitosis (clonal expansion)
- clones becomes plasma cells which produce and secrete (monoclonal) antibodies complementary with antigen.
- Clones become memory B lymphocytes which remain in blood and recognise antigen for a more rapid response and release of more antibodies upon second infection.
Describe the Structure of HIV
- genetic material is RNA
- contained in a capsid
- contains Reverse transcriptase
- Phospholipid envelope
- has Attachment proteins on lipid envelope
Describe how HIV replicates
- Attachment proteins complementary and bind to proteins on T helper cell.
- Capsid broken down and releases viral RNA
- Reverse transcriptase converts viral RNA to cDNA.
- Viral cDNA incorporated into host DNA (NOW INFECTED).
- Transcription of viral DNA into mRNA
- Translation of HIV proteins and formation of virions (infectious particle)
Virions bud off the host cell membrane forming their lipid bilayer.
Describe antigen
An antigen is a molecule (usually a protein) that stimulates an immune response that results in the production of a specific antibody from a specific B plasma cell.
Describe the cell mediated response
Specific T helper cell binds to antigen presenting cell and goes through clonal selection.
Release cytokines which:
Stimulates (attract) phagocytes
activate cytotoxic killer T cells
activates specifically complementary B lymphocyte
Form memory T cells.
Describe the role of cytotoxic T cells
Destroys cancer cells OR cells infected by a virus
By releasing perforin
Creating holes in cell surface membrane of the Antigen presenting cell (->[don’t write but so you know.. this is any cell with cancer markers or infected by a virus in this case)
Causing cell lysis
Key: destroys one’s own cells.
Describe the Humoral response
Specific T helper cell bind to specifically complementary B lymphocyte and releases cytokines.
clonal expansion of B lymphocyte.
B lymphocytes differentiate into plasma cells or memory B cells.
Plasma cells produce and secrete specific antibodies complementary to one antigen.
Memory cells involved in secondary response.
Describe the primary and secondary response
No antibodies due to no exposure to antigen.
Latent period -The time that passes between being exposed to an antigen and having symptoms.
Primary response (1st response to antigen)
clonal expansion of specific B lymphocyte into plasma cells.
Plasma cells produce and secrete antibodies.
Secondary response (2nd exposure to antigen)
Shorter latent period
Memory cells divide into large numbers and create plasma cells.
Produce more antibodies more rapidly.
Contrast passive and active immunity
- Active involves memory cells whereas passive does not.
- Active involves production of antibody by plasma cells / memory cells whereas passive antibody is introduced from outside body (eg breast milk/antivenom ect)
- Active long term, because antibody produced in response to antigen whereas passive is short term, because antibody is broken down.
- Active takes time to develop as requires formation of memory cells whereas, passive fast acting as antibodies given directly.
Describe indirect ELISA tests
First antibody complementary to antigen on well
WASH to ensure unbound antibodies are removed
Second antibody, with enzyme attached, added and complementary/binds to first antibody
WASH to ensure unbound antibodies, with enzyme attached, are removed
Substrate for enzyme added causing colour change
Describe sandwich ELISA tests
Antibody, that is fixed to the well, binds to complementary antigen in sample.
wash to ensure unbound antigens are removed
Second antibody, with enzyme attached, added and binds to antigen-antibody complex.
wash to ensure unbound antibodies, with enzyme attached, are removed
Substrate for enzyme added causing colour change
Describe antibody
An antibody is a protein specific to one antigen, produced by a specific plasma cell
Describe how vaccination leads to production of antibodies and immunological memory
- Vaccine contains antigen from pathogen.
- Phagocyte engulfs and presents antigen on its surface.
- T helper lymphocyte with complementary receptor protein binds to antigen.
- T helper lymphocyte releases cytokines to stimulate specific B lymphocyte to divide by mitosis (clonal expansion)
- Clones becomes plasma cells which produce and secrete (monoclonal) antibodies complementary with antigen.
- Clones become memory B lymphocytes which remain in blood and recognise antigen for a more rapid response and release of more antibodies upon second infection.
Describe the structure of HIV
- Genetic material is RNA
- Contained in a capsid
- Contains Reverse transcriptase
- Phospholipid envelope
- Has Attachment proteins on lipid envelope
