Immunology

Immunology

1. first line of defense : External physical barrier

2. secod line : internal barriers

3. third line : specific immune responses

   • humoral immunity
     • protection through antibodies
       • antigen binding sites -> epitopes -> function -> give protection
       • blocks attachment of toxins
       • blocks adhesion of bacteria
       • blocks adhesion of viruses
       • neutralisation of toxin
       • agglutination
       • opsonisation
       • activation of complement
       • antibody-dependent cell mediated cytotoxicity
     • cell mediated immunity
       • overcome by :
         • CD8 cytotoxic T cell
           • granule exocytosis
             • recognition and binding of target cells -> delivery of lethal hit -> death of target cells -> recycling of cytotoxic T cells
             • -granule contain - perforin & serine proteases
           • fas pathway
             • Binding of TcR and antigen
               • granule exocytosis
                 • triggers expression fas-ligand on Tc cell
                   • Fas on target cell cross-linked with fas-L
                     • APOPTOSIS
         • Delayed-type hypersensitivity response
           • recruit monocytes
           • keep macrophages at site of infection
           • activate the monocytes and macrophage
           • 1.Activation of CD4 T cells
             • 2. Migration of effector Th cells
               • 3. Recruitment and retention of monocytes
                 • Activation of macrophage
                   • 5. Elimination of pathogens in DTH reactions
   • acquired immunity
   • involves lymphocytes
     • lymphocyte B
     • B cell
     • T cell
       • CD4 surface protein
         • TH1 cells
         • TH2 cells
       • CD8 surface protein
         • Tc cells

4. Organs of immune system

   • primary lymphoid organs
     • production sites
     • maturation sites (absence of antigen)
   • secondary lymphoid organs
     • maturation sites - antigen-driven immune cells

5. non-specific immune responses

   • internal innate immunity
     • 2nd line defense
     • mechanisms protection
       • physiological barrier
       • phagocytosis
       • inflammation
   • external innate immunity
     • 1st line defense
     • prevent penetration of pathogens into tissue

6. Antigen

   • trigger specific immune response & react with product of responses
   • Antigenic determinants sites
   • carrier - antigen itself

7. Antibody

   • combine with antigenic determinants
   • important components for specific immune responses
   • Basic structure : Y
   • 2 Light chain (L) & 2 heavy chain (H)
   • classes
     • IgA
     • IgG
     • IgM
     • IgD
     • IgE

8. mechanism of antibody production

   • APC ingest antigen -> present to TH1 cells -> IL2 released -> stimulate proliferation and differentiation of TH cell into TH2 cells
     • secrete cytokines -> stimulte B cells -> antigen specific B-cell clone produced
       • differentiation
         • plasma cells (short-lived 1 week)
           • antibody secreted
         • memory cells (long-lifetime)