1 / 29

ANTIBODIES – IMMUNOGLOBULINS

ANTIBODIES – IMMUNOGLOBULINS. Definition:- Antibodies are defined as specialized serum proteins that are formed in response to an antigen and react specifically with that antigen or one very closely related to it in some observable manner. NATURE:-

priebe
Download Presentation

ANTIBODIES – IMMUNOGLOBULINS

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. ANTIBODIES – IMMUNOGLOBULINS

  2. Definition:- Antibodies are defined as specialized serum proteins that are formed in response to an antigen and react specifically with that antigen or one very closely related to it in some observable manner.

  3. NATURE:- • Chemically antibodies are : Globulins • They comprise 20 – 25%, of total serum proteins. • Electrophoreticallymigrate to gamma region. • Immunoglobulin includes: • Antibody globulins • Abnormal plasma proteins of myeloma. • Cryoglobulin • Macroglobulin

  4. All Immunoglobulins are not antibodies. All antibodies are immunoglobulins. Immunoglobulins are principally synthesized by plasma cells & B lymphocytes.

  5. Functions:- Elimination of foreign antigen from the circulation. Recruitment and enhancement of host effector mechanism Measurement of antipathogen antibody levels in diagnosis. Passive administration of pooled antibodies for host therapy.

  6. Structure of immunoglobulin : Ig :- Glycoproteins Two pairs of polypeptide chains of diifferent sizes. Smaller - L light chains Larger - H Heavy chains. L chain mol.wt :- 25,000 H chain mol.wt :- 50,000

  7. H Chains : Immunoglobulin classH Chain Ig G γ (Gamma) Ig A α (Alpha) Ig M μ (mu) Ig D δ (Delta) Ig E ε (Epsilon) L Chains:Kappa - κ Lambda- λ Kappa : Lambda = 2 : 1

  8. Antigen combining site : Aminoterminus FC fragment : Carboxyterminal portion of H Chains. Determines the biological properties of Ig molecule: Complement fixation Placental transfer Skin fixation & Catabolic rate. Fab – (V L and V H) Specific antigen binding site.

  9. Immunoglobulin classes:- Human sera contains: Ig G, Ig A, Ig M, Ig D, and Ig E, in the descending order of concentration.

  10. Ig G: • Major serum immunoglobulin – 80% • Mol. Wt : 150,000(75) • Distributed equally between intravascular and extravascular compartments. • Half life : 23 days. • Normal Serum Conc : 8 – 16 mg per ml.

  11. Ig G:- Only maternal Ig transported across the placenta and provides natural passive immunity. Ig G – Enhances phagocytosis. Ig G complexes with platelet FC receptors  Aggregation and vasoactive amine release. Ig G can fix to guinea pig skin.

  12. Participates in complement fixation & precipitation. Neutralization of toxins General purpose antibody Protective against blood and tissue infectious agents. Suppresses homologous antibody synthesis.

  13. Ig G : Late antibody. 4 classes : Ig G, G2, G3, G4 – Each a distinct gamma chain. Ig G1 : G2 : G3 : G3 = 65%, 23%, 8%, 4%.

  14. I g A :- 10 – 13% of serum immunoglobulins. Normal serum level : 0.6 – 4.2 mg/ml. Half life : 6 – 8 days Major Ig in : Colostrum, Saliva, tears.

  15. 1. Serum Ig A : Monomer Mol. Wt : 160,000 2. Secretory Ig A : Dimer with a ‘J’ chain Secreted by plasma cells. Secretory piece : Produced by mucosal or glandular epithelial cells.

  16. Mol. Wt : 400,000. Local immunity : By forming an antibody paste. Ig A can activate the alternate complement pathway. Two subclasses : Ig A1, and Ig A2 Ig A2 : Lacks interchaindisulphide bonds. : Minor component of serum Ig A but Dominant in secretions.

  17. Ig M : 5 – 8% of serum Igs. Normal level: 0.5 – 2.0 mg / ml Half life : 5 days. Heavy molecule M.W : 10,00,000 Millionaire molecule. Polymer of five four – peptide sub units.

  18. Mostly intravascular. Oldest immunoglobulin class Earliest Ig synthesized by fetus. Presence of IgM : Indicates intrauterine Infection & In cong. infections such as Syphilis, Rubella, HIV & Toxoplasma

  19. Short lived : Hence indicates recent Infection. 0.12 M 2 – Mercaptoethanol : Destroys IgM IgM : Immune hemolysis More effective than Ig G in opsonisation Bactericidal action & bactrerialagg Protection against : Blood microbes Ig M deficiency : Septicemias

  20. Ig D: Serum conc: 3 mg per 100 ml Mostly intravascular Half life : 3 days. Occur on the surface of un stimulated B lymphocytes.

  21. IGE : By Ishizaka MW: 190,000 Half life : 2 days. Inactivity at 56°C in one hour. Affinity for mast cells. Mostly extra vascular.

  22. Elevated IgE in :- Asthma, hay fever& eczema, parasitic diseases. Produced in linings of the respiratory & intestinal tracts. Responsible for anaphylaxis. Protection against pathogens by mast cell degranulation.

More Related