Haptens

Haptens

1. HAPTENS Presentation on : Presented By: Sonika Bhatnagar B.Sc Life Sc (III )

2. Introductory Terms: Antigen is a molecule that can bind to an antibody, B cell receptor or T cell receptor A stimulus that produces a humoral or cell-mediated immune response All immunogens are antigens but not all antigens are immunogens Some very small molecules called haptens can bind to Ab’s or TCR’s but they cannot initiate an immune response… Antigen Immunogen

3. Haptens The term Hapten was given by the immunologist Karl Landsteiner, who studied them in early 20 th century. It came from a Greek word Haptein meaning to fasten.

4. Haptens

5. Why Haptens are not Immunogenic?

6. Haptens can induce immune response when covalently bound to a large protein called a ‘carrier protein’ forming Immunogenic Hapten -Carrier Conjugate . Carrier protein molecule are antigenic as well as immunogenic. A peptide of the carrier protein is presented in association with class II MHC protein to the helper T cells . The activated helper T cells then produce interleukins, which stimulates the B cells

7. Carrier Protien Do not activate B-cells Activate B-cells

8. Animals immunized with such a Hapten conjugate produce antibodies specific for : the hapten determinant, (2)unaltered epitopes on the carrier protein (3 ) new epitopes formed by combined parts of both the hapten and carrier

9. By itself, a hapten cannot function as an immunogenic epitope . But when multiple molecules of a single hapten are coupled to a carrier protein (or nonimmunogenic homopolymer ), the hapten becomes accessible to the immune system and can function as an immunogen . THUS,

10. Pioneering work of Karl Landsteiner Hapten molecule injected No antibodies raised Carrier Molecule injected Hapten -Carrier Conjugate A ntibodies raised against the carrier molecule injected Anti-serum Anti-serum Anti-serum

11. Pioneering work of Karl Landsteiner ( contd …)

12. By observing which hapten modifications prevented or permitted cross-reactions, Landsteiner was able to gain insight into the specificity of antigen antibody interactions Pioneering work of Karl Landsteiner ( contd …) Landsteiner immunized rabbits with a hapten -carrier conjugate and then tested the reactivity of the rabbit’s immune sera with that hapten and with closely related haptens coupled to a different carrier protein He was thus able to measure, specifically, the reaction of the antihapten antibodies in the immune serum and not that of antibodies to the original carrier epitopes Landsteiner tested whether an antihapten antibody could bind to other haptens having a slightly different chemical structure. Such reactions are called a cross-reaction Antibodies developed against aminobenzene or its derivatives react only with the original hapten and do not cross react with any other derivative.

13. Examples of Haptens Many biologically important substances which can function as haptens are:- Drugs- such as Penicillin peptide hormones steroid hormones Some important Haptens are: Dinitrophenol Aminobenzene o - aminobenzoic acid m- aminobenzoic acid P- aminobenzoic acid

14. T he formation of drug-protein conjugates in the body can produce drug allergies that may be life-threatening. Haptens in Real life... Immunologist’s favourite , as it can be used as- DIAGNOSTIC TOOL Enzyme-multiplies Immunoassay Technique (EMIT )

15. Allergy to Drugs Other drugs which may elicit allergy streptomycin, aspirin, the so-called “ sulfa -drugs” such as the sulfonamides , some anesthetics (e.g., succinyl choline), and some opiates.

16. Application of Haptens in Pregnancy test

17. References http ://books.google.co.in/books?id=QCFwJYk2m4YC&pg=PA37&lpg=PA37&dq=example+of+peptide+hormone+as+hapten&source=bl&ots=INNSWFE6O_&sig=AMmrqCTXEk-WUf6wF6Mqo90acL8&hl=en&sa=X&ei=brBOVKPLCaLbmAXymYGYBA&ved=0CCsQ6AEwAw#v=onepage&q=example%20of%20peptide%20hormone%20as%20hapten&f=false http ://www.slideshare.net/RajkumarNarasinghan/antigen-15639219?qid=f2c646e7-0642-4990-8372-c4c88e4a6e2d&v=default&b=& from_search=10 http:// www.slideshare.net/taha244ali/2-antigens-immunogens-epitopes-and-haptens Immunology Kuby 6 th Edition