Antigen-Antibody Interactions

1. Antigen-Antibody Interactions Dr. Conrad Sept. 9, 2009

2. Antigenicity • Requirements to be an immunogen • Low mw antigens (haptens) • Adjuvants • Primary vs secondary responses

5. Concept of a Hapten

8. r/c = Kn-Kr c = concentration of free antigen (hapten) K = Ka = equilibrium constant r = hapten bound per unit Ab n = Valence of Ab

11. Polyclonal Ab

12. 1/c = K(2) – K(1) 1/c = K0

13. Factors which influence Ab affinity • Temp, pH, ionic strength • Polyclonal vs monoclonal • Ab class • Type of antigen

14. Antibody Combining Site Location

19. All interactions are non-covalent

21. Evidence that Hv interacts with Ag 3 lines of evidence

22. Affinity Labeling

23. Comparison of Hv sequences of monoclonals binding the Same vs binding a different antigen epitope

25. Multivalent AgAb

27. Affinity vs avidity – depends on valence Avidity – sum total or strength of binding of two molecules (or cells) to one another at multiple sites. Distinct from affinity which is the strength of binding of one site on a molecule to its ligand.

28. IgM is the most avid of Ab classes

30. Composition of immune ppts at different Ab/Ag ratios

31. Gel Diffusion Analysis to determine relatedness of antigens

32. Cross-reactivity

35. Nature of Antigenic Determinants

36. Example of a determinant that depends on secondary structure

38. Biologic Function of Antibodies

40. Immune Components that Interact with Antigen • Antibody – intact antigen • MHC – antigen fragment • TCR – antigen fragment

42. Analytical uses of antibodies Preparation of mutant mice

46. ELISA RIA

47. Affinity Chromatography

48. Immunoprecipitation

49. Western Blotting

50. Immunofluorescence