3 Antigens and recognition Flashcards
antigen recognition
Once seen something more likely to recognise it and quicker
Focused response to the specific microbe - even parts of the microbe
antigens
trigger adaptive immune response – specific
anything that the adaptive immune system that can have an immune response to
B (antibodies) and T (cellular immunity) lymphocytes
antigen determinants
specific place where antibody binds to antigen
antigen: antibody interaction
Y shaped molecule
Different antibodies may be able to bind to the same antigen at different areas of it
Antigenic determinants – specific place where antibody binds to antigen
Antibody from a B cell
Antibody arms recognise an epitope – exact same binding site on both the arms
epitopes on antigen
Epitope bound is antigen combining site – variable in different antibodies (peptide sequence that makes up this epitope varies = different specificity)
epitope recognition
Antigen recognition by B lymphocytes
B lymphocytes start with antibodies they make bound onto the cell as a receptor, cell can interact with pathogen if binds the cell can be turned on by other cells to make plasma cells which make many antibodies
clonal selection
Proposed to explain how a single B or T cell that recognizes an antigen that enters the body isselectedfrom the pre-existing cell pool of differing antigen specificities and then reproduced to generate aclonalcell population that eliminates the antigen.
From single activated B cell can get many clones
Clones can become plasma cells – antibodies against pathogen, some become memory cells for the future
secondary response
Antigen binding sites genes become altered those that are more specific survive and those that are less specific die – in secondary response
vaccinations
Inactivated toxin - toxoid
If introduced toxoid into body – immune response so have memory, will response fully to it if get toxin in body
Immunological memory recognises antigen
Multiple doses of vaccine – improve immune response and how they can target that pathogen
B cell receptors
B cell the antibody attached made of four chains – two light two heavy, (light identical and heavy are identical)
Combining sites are at the tips of where the heavy and light chains come together
When part of B cell receptor have cytoplasmic tail
T cell receptors
T cell receptor similar as have heavy and light chains
T cell receptor is never released from plasma membrane
When antibody produced bind to the pathogen - B
T cells do not do anything to the pathogen directly, they help other cells do their jobs better
T helper cells
T helper cells
- B cells –>antibody production
- Macrophages –> phagocytes and killing
T cytotoxic cells
kill –> infected cells
B and T cell recognition of antigen
B cell can directly bind to the antigen
T cells have to see fragments of an antigen not the whole
Protein goes into cell is digest and shown to T cells if t cell interacts with presented peptide becomes activated – can then activate B cells etc
HLA 1 and 2 Glycoproteins
Surface of T cell
Interact with slightly different antigen presenting proteins
HLA class 1 and 2 differ
HLA 2 present slightly longer
