B Cells + Antibodies

B Cells + Antibodies

1. Antibody + TCR structures

   • S6-S9
   • Antibody structure 8 Hinge S12
   • Summary
     • 4 polypeptide chains, heavy + light chains, variable + constant regions on each chain, Fab + Fc fragments, Hinge + di-sulphide bonds link the chains
     • CDR on each chain forms 2 antigen binding sites per molecule
     • Hinge allows X-linking of Ab + agglutination/ precipitation of Ag
     • Ab isotypes (IgM/D/G/E/A)
     • Ab idiotypes (unique to each cell)

2. Importance of CDR (Complementarity Determining REgion)

   • Complementarity determining regions (CDRs) are part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen

3. Antibody Isotypes + Idiotypes

   • ISOTYPES- Ab which vary in the constant region IDIOTYPES- Ab which vary in variable region (antigen binding specificity)
   • Variation in heavy chain sequence corresponds to isotype class of antibody in humans: IgM, (IgD), IgG, IgE and igA Heavy chains are referred to as M,D, G,E&A many dogs and goats eat apples,
   • B cells can produce all 5 types of Ab but ONLY ONE @TIME + they SWITCH IN THE ORDER ABOVE + NEVER REVERSE
   • S20-29

4. Properties of Antigens

   • S15-16
   • Epitopes of a Protein Ag can be linear. Linear epitope of protein antigen is formed from contiguous amino acids, discontinuous epitope (conformational epitope) is formed from amino acids from different parts of polypeptide that are brought 2gether when chain folds i.e. are dependent on conformation of the protein (S18)

5. Antibody effector functions - Antibodies do stuff

   • 1) Neutralisation
   • 2) Opsonisation + agglutination
   • 3) Complement Activation
   • 4) Antibody dependent cell-mediated cytotoxicity
   • see S31-End for details of 1-4 and mojre

6. Difference between monoclonal + polyclonal antibodies

7. Focus on cells of innate system- dendritic cells + macrophages

8. S2

9. Antibodies = proteins, chains of amino acids, overall 3D structures, alpha helices + Beta sheets are common conformations within proteins, (S4-S5)

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