SPECIFIC IMMUNITY Properties of Immunity Acquired Immunity

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SPECIFIC IMMUNITY Properties of Immunity Acquired Immunity Powered By Docstoc
					       SPECIFIC IMMUNITY
2 CATEGORIES:
1.  Innate --genetically determined;
           --no prior exposure or
           antibody production involved.

2.     Acquired --produced by prior exposure
                or antibody production.
                     SPMD 202




        Properties of Immunity
              1.   Specificity
              2.   Versatility
              3.   Memory
              4.   Tolerance




                     SPMD 202




          Acquired Immunity
     Immune cells recognize and memorize
     exposure to a foreign agent.
     --cell-mediated
     --antibody-mediated




                     SPMD 202




                                               1
    Cell-Mediated Immunity
• Activated lymphocytes
• Attack & kill cancers and other foreign
  agents.
     Cytotoxic T cells (TC)
     Helper T cells (TH)
     Suppressor T cells (TS)


                    SPMD 202




    Cytotoxic T Cell Function




 • Cytotoxic T cell binding to cancer cell.
                    SPMD 202




          T Cell Activation
ANTIGEN PRESENTATION
• Foreign cells are processed by other cells
  (typically macrophages) which break up
  the antigen and present part of that
  antigen to lymphocytes.

• antigen incorporated into the major
  histocompatibility complex (MHC).
                    SPMD 202




                                               2
           T Cell Activation
ANTIGEN RECOGNITION
• T cell is programmed to recognize the
  presence of specific bound antigens.
• CD (cluster designation) markers
  TC & TS ⇒ CD8+ T cells (functionally
                 different)
        TH ⇒ CD4+ T cells
                    SPMD 202




           T Cell Activation
• CD8 T cells activated by Class I MHC
  proteins (on all nucleated body cells)
  ⇒ cell-mediated immunity

• CD4 T cells activated by Class II MHC
  proteins (present only on antigen
  presenting cells)

                    SPMD 202




                 TH Cells
• Regulate the immune responses
--release soluble factors (lymphokines) which:
  1. Stimulate proliferation of T & B cells
  2. Stimulate the killing activity of other
      T cells



                    SPMD 202




                                                 3
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                                SPMD 202




          Cytotoxic T Cells
“Killer T Cells”
Destroy antigen-bound targets by:
1.   Rupturing the antigenic cell membrane
     through the release of perforin.
2.   Killing the target cell by secreting
     lymphotoxin.
3.   Activating suicide genes in the target’s
     nucleus.
                               SPMD 202




          Cytotoxic T Cells
 Memory T Cells
 --prepare for second exposure.
 --remain in reserve ⇒ immediate future
   response.




                               SPMD 202




                                                                    4
             Suppressor T Cells
Suppress the response of other T cells and B
  cells.
--secrete inhibitory cytokines
--slow acting; in essence “put on the brakes”
  and limit the degree of immune system
  activation.


                        SPMD 202




 Antibody-Mediated Immunity
1.        Virus, bacteria, or foreign protein
          enter the cell.
2.        Ingested by macrophage.
3.        Exposes part of the antigen (major
          histocompatibility complex--MHC).
4.        Antigen presenting cell (APC)
          contacts lymphocytes.

                        SPMD 202




 Antibody-Mediated Immunity
     5.      T cells activated (CD4+ Helper)
     6.      Helper cells stimulate B cells
     7.      B cells proliferate
             Plasma & Memory Cells
     8.      Antibody is produced.



                        SPMD 202




                                                5
 Antibody-Mediated Immunity
B cells produce antibodies

• Variable region binds to the      S                       S•
                                 S•                            S
  antigen                                  S         S•
                                        S•              S

• Constant region binds to                     S•S

  receptors; determine the                     S•S

  way the antibody is secreted
  and how it is distributed

                      SPMD 202




 Antibody-Mediated Immunity
B cells produce antibodies

• Variable region binds to the      S                       S•
                                 S•                            S
  antigen                                  S         S•
                                        S•              S

• Constant region binds to                     S•S

  receptors; determine the                     S•S

  way the antibody is secreted
  and how it is distributed

                      SPMD 202




 Antibody-Mediated Immunity
B cells produce antibodies

• Variable region binds to the      S                       S•
                                 S•                            S
  antigen                                  S         S•
                                        S•              S

• Constant region binds to                     S•S

  receptors; determine the                     S•S

  way the antibody is secreted
  and how it is distributed

                      SPMD 202




                                                                   6
        Classes of Antibodies
       (Immunoglobulins--Ig)
IgG --most common type found in serum
    --responsible for resistance against
    many kinds of viruses, bacteria, and
    bacterial toxins.
IgA --found in glandular secretions (saliva,
    tears, lung, and respiratory tract)
IgM --the first antibody type secreted after
    an antigen arrives.
                   SPMD 202




        Classes of Antibodies
       (Immunoglobulins--Ig)
IgE --releases chemicals (histamine) that
    accelerate inflammation.
    --present in large amounts in people
    with allergies.
IgD --located on the surfaces of B cells.



                   SPMD 202




  Antigen-Antibody Complex
 Formation of Ag-Ab complex may eliminate of
 the Ag 7 different ways:
 1. Neutralization
 2. Agglutinization
 3. Activation of the complement system
 4. Attraction of phagocytes
 5. Opsonization
 6. Inflammation
 7. Prevention of bacterial & viral adhesion
                   SPMD 202




                                               7
                           Adapted Immunity



           Active Immunity                     Passive Immunity
        produced by antibodies                 produced by transfer
       that develop in response                 of antibodies from
              to antigens                         another person




                                    SPMD 202




                           Adapted Immunity



           Active Immunity                     Passive Immunity
        produced by antibodies                 produced by transfer
       that develop in response                 of antibodies from
              to antigens                         another person




      Natural               Artificial/Induced
    develops after             antigens are
exposure to antigens      deliberately introduced
   in environment               in a vaccine




                                    SPMD 202




                           Adapted Immunity



           Active Immunity                     Passive Immunity
        produced by antibodies                 produced by transfer
       that develop in response                 of antibodies from
              to antigens                         another person




                                Natural                 Artificial/Induced
                         maternal antibodies are      antibodies produced by
                       transferred across placenta       another person or
                             or in breast milk          animal are injected




                                    SPMD 202




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Description: SPECIFIC IMMUNITY Properties of Immunity Acquired Immunity