1 / 21

Immunology Chapter 6, Lecture 1

Immunology Chapter 6, Lecture 1. Richard L. Myers, Ph.D. Department of Biology Southwest Missouri State Temple Hall 227 Telephone: 417-836-5307 Email: rlm967f@mail.smsu.edu Homepage: http://creative.smsu.edu/biology/myersr/index.html TopClass: http://creative.smsu.edu.

maddy
Download Presentation

Immunology Chapter 6, Lecture 1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ImmunologyChapter 6, Lecture 1 • Richard L. Myers, Ph.D. • Department of Biology • Southwest Missouri State • Temple Hall 227 • Telephone: 417-836-5307 • Email: rlm967f@mail.smsu.edu • Homepage: http://creative.smsu.edu/biology/myersr/index.html • TopClass: http://creative.smsu.edu

  2. Antigen-Antibody interactions • Similar to enzyme-substrate reactions • Involves noncovalent interactions • between epitope and CDRs of antibody • the reaction is very specific • used in diagnosing disease • monitoring level of the humoral response • identifying certain molecules • Ag-Ab reactions differ and speed and sensitivity

  3. Strength of Ag-Ab reactions • Involves noncovalent interactions • hydrogen bonds • ionic bonds • hydrophobic interactions • van der Waals interactions • Requires many of these interactions • operating over a small distance (1 angstrom) • Therefore, depends upon a very close fit

  4. Antibody affinity • Defined as the strength of the sum total of noncovalent interactions • Low-affinity antibodies bind antigen weakly • High-affinity bind more tightly • Ag-Ab association can be determined by equilibrium dialysis

  5. Antibody avidity • Defined as the strength of multiple interactions between multivalent antibody and antigen • IgM has a low affinity compared to IgG, but has a high avidity

  6. Cross-reactivity • Ag-Ab reactions are highly specific, but • Ab may cross-react with an unrelated Ag • affinity is usually less • An example of a cross-reacting Ab is the ABO blood-group antigens • originally elicited by microbial antigens • will cross-react with similar antigens on RBCs

  7. Precipitin reactions • Results when antigen and antibody interact • Forms a lattice that becomes visible • antibody must be bivalent • called precipitins • Reaction may take place in fluids • dilute the antibody, hold antigen constant • used as a rapid test for presence of Ag or Ab • the interfacial or ring test is very useful

  8. Precipitin reactions (cont) • Reactions may occur in gels • produces a visible line of precipitation • called immunodiffusion • used to determine relative concentration of Ag or Ab • used to compare antigens • or determine relative purity of an antigen • Mancini method (radial diffusion) • antigen placed in a well • diluted antibody placed into agar

  9. Precipitin reactions (cont) • Ouchterlony method • double diffusion in agar • antigen and antibody diffuse toward each other • form visible precipitation line where they meet • show relationships between different systems • identity • nonidentity • partial identity

  10. Precipitin reactions (cont) • Immunoelectrophoresis • seperation of proteins with electrophoresis • followed by double diffusion in gel • can detect concentrations of 3 - 20 mg/ml • rocket electrophoresis is similar but can detect level of protein as low as 0.2 mg/ml • 2-D immunoelectrophoresis • electrophoresis followed by overlay with gel with antiserum

  11. Assignment • Read Chapter 6, Antigen-Antibody Interactions • Review question 6 (pg 163)

More Related