Term | Definition |
Specific Immunity | The Third and final Line of defense |
Specific Immunity | Acquired only after an immunizing event
example: Infection or Vaccination |
Immunocompetence | The body's ability to react to foreign substances |
Immunocompetence | Development of B and T LYMPHOCYTES |
Two Characterizing features of the third line of defense | specificity and memory |
What does Specificity and Memory do in the third line of defense? | Only recognize certain (specific) pathogens |
Antigen | anything foreign that activate B-cells and T-cells |
Immunogen | Any substance that induces a state of sensitivity or resistance after processing by the immune system of the body. |
Major Histocompatibility Complex (MHC) | series of glycoproteins (MHC molecules) found on the surface of all cells EXCEPT red blood cells |
Red Blood Cells and MCH | Red blood cells have its own markers |
If MCH is ABSENT, what will happen to the cell? | The cell will be destroyed by the immune system |
MHC | mark Self verses Self |
MHC | present antigens |
Development of the Dual Lymphocyte System | B-cells and T-cells work together |
Development of the Dual Lymphocyte System | High level of communication between the two cell types |
Development of the Dual Lymphocyte System | When antigens are presented, both B-cells and T-cells are activated |
Steps of the Development of the Dual Lymphocyte System | Step 1: Lymphocyte Development
Step 2: Presentation of Antigens
Step 3 and 4: T-cell Response |
Step 1: Lymphocyte Development | All lymphocytes arise from the same basic stem cell type |
Where do Lymphocytes come from? | come from pluripotential |
What is Pluripotential? | Stem cells having the developmental plasticity to give rise to more than one type. Example: undifferentiated blood cells in the bone marrow. |
Step 1: Lymphocyte Development- Final Maturation for B-cells | Occurs in specialized Bone Marrow sites |
Step 1: Lymphocyte Development- Final Maturation for T-cells | Occurs in the Thymus |
Step 1: Lymphocyte Development- After maturation of B-cells and T-cells | Both cell types migrate to separate areas in the lymphoid organs
"going to the dump to shop" |
Specific Events in B-cell Maturation | Bone marrow sites harbor stromal cells
Stromal cells nuture the lymphocytes stem cells and provide chemocal signals that initiate B-cell development
B-cells circulate through the blood, "homing" to specific sites in lymph nodes, spleen, and GALT |
Specific Events in B-cell Maturation | Adhere to specific binding molecules where they come into contact with antigens |
B-Cell Receptor | Immunoglobulim receptors (Igs)
Y-shaped arrangement
Ends of forks (of y shape) contain pockets called the antigen binding sites
Can be highly variable in shape to fit a wide range of antigens
Variable regions (V)-folk
Constant regions (C)-handle |
Specific Events in T-Cell Maturation | Directed by the thymus gland and its hormones
Circulate between the lymphatic and circulatory system, migrating to specific T-cell areas of the lymph nodes and spleen
Mature T lymphocytes express T-cell receptor and co-receptors (CD-4 or CD-8) |
T-Cell Receptor | Constant Region
Variable Region
Antigen binding site
Co-Receptor
Never Secreted; always attached |
Immunological Diversity | 500 gene segments that can be rearranged t produce diverse receptor types |
Immunological Diversity | *Different B and T cells are made which leads to specificity
*By the time B and T cells reach the lymphoid tissue they are equipped to respond to a single, unique antigen
*Each line of lymphocytes is termed a clone |
Step 2: Presenttation of Antigens | Perceived as foreign
Antigenic Molecule |
Antigenic Molecule: Proteins and polypeptides | Enzymes, cell surface structure, hormones, exotoxins |
Antigenic Molecule: Lipoproteins | Cell membrane |
Antigenic Molecule: Nucleoproteins | DNA complexes to proteins but not pure DNA |
Antigenic Molecule: Polysacchararides | Certain bacterial capsules |
Antigenic Molecule: Haptens | small foreign molecules that are too small to elicit an immune response on their own
*if linked yo a larger carrier molecule, them the combination develops IMMUNOGENICITY |
Role of antigen processing and presentation | *Produce APCs
*Engulf the antigen and modify it so it is more immunogenic and recognizable - Epitope
*After processing, the antigen is bound to the MHC receptor and moved to the surface of the APC so it is accessible to T lymphocytes |
What is APC? | APC (Antigen-presenting cells): cells that act upon and formally present antigens to lymphocytes
*Macrophages
*Dendritic cells (related to macrophages)
*B cells |
Step 3 & 4: B-Cell Response | Activation of B Lymhocytes |
Activation of B Lymhocytes | *Clonal section and binding of antigen
*Antigen processing and presentation
*B-cell/ T-cell recognition and copperation (T- Helper)
*B-cell activation
*Clonal expansion (copies)
*Antibody production and secretion
*Plasma cells and memory cells |
What are Memory Cells? | Long term B-cells |
What are Plasma Cells? | Antibody producer factors that is fighting right now |
Classes of Immunoglobulins (Igs) | B cell receptors (weight and arrangement)
IgM- 1st one made during an infection
IgA- important in mucosal defense
IgD- acts as a receptor
IgG- most prevalent AB
IgE- Allergies |
Antigen- Antibody Interactions | Principal activity of antibody: unite with , immobilize, call attention to, or neutralize the antigen for which it was formed |
Antigen- Antibody Interactions : Opsonization | plasma cells- antibody marks to kills |
Antigen- Antibody Interactions: Neutralization | not allowing microorganisms to attach |
Antigen- Antibody Interactions: Agglutination | accumulate; stick together which prevents it from doing what its suppose to do |
Antigen- Antibody Interactions: Complement fixation | antibodies cause complement and produce MACs (donuts) which cause them to die |
Antigen- Antibody Interactions: Antitoxin | Antibodies going totoxin don't allow it to find its target and it dies |
Monitoring Ab Production: Primary Response | *First exposure
*Latent period- lack of antibodies synthesis
*Synthesis of antibodies -first IgM, second IgG, then some IgM ad IgA
*Titers (In immunochemistry, a measure of antibody level in a patient, determined by agglutination methods.) |
Monitoring Ab Production: Secondary Response | *Re-expossre to the same immunogens
*Antibody synthesis, titer, and length of antibody persistence is rapid and amplified
*primary due to memory cells |
Step 3 & 4: T- Cell Response | Cell-Mediated Immunity (CMI) |
Cell-Mediated Immunity (CMI) | *require the direct involvement of T lymphocytes throughout the course of the reaction
*T cells require some type of MHC recognition before they can be activated
*T cells stimulate other T cells, B cells, and phagocytes
*Cytokine production |
What is Cytokine production? | production of chemicals produced by T- cells |
T cell Activation and Differentiation | *Recognize an antigen only with an MHC carrier
*T cell is sensitized when an antigen/ MHC complex is bound to its receptors
*The activated T cells then transform in preparation for mitotic divisions and differentiate into one of the subsets |
T Helper Cells (T H) | *Play a central role in regulating immune reactions to antigens
*Involved in activating Macrophages
-directly by receptor contact
-indirect y by releasing cytokines |
T Helper Cells (T H) | *Secrete interleukin-2 (type of cytokine)
*some secrete interleukin- 4,5, and 6 (help activate B-cells) |
T Helper Cells (T H): Secrete interleukin-2 | stimulates the primary growth and activation of many types of T cells |
T Helper Cells (Th): secrete interleukin- 4,5, and 6 | stimulate various activities of B-cells |
Regulatory T Cells (Tr) | *T-cells regualte
*Maintain "Happy Medium"
*Carry CD4 markers
*Control Inflammation
*Prevent Autoimmunity
*Prevent immune response against normal flora |
Cytotoxic T Cells (Tc) | *Cytotoxicity
*Target cells that Tc cells can destroy include: Virally infected cells, cancer cells, and cells from other animals and humans
*After activation the Tc cell severely injures the target cell- secrerion of perforins and granzymes |
What is Cytotoxicity? | the capacity to kill a specific target cell |
What are Perforins? | Proteins released by cytotoxic T cells that produce pores in target cells |
What is Granzymes? | Enzymes secreted by cytotoxic T cells that damage proteins of target cells. |
Natural Killer Cells (NKC) | *Related to T- cells
*Lack specificity for antigens
*Circulate through the spleen, blood, and lungs
*Probably the first killer cells to attack cancer cells and virus-infected cells |
Vaccines | Whole bacterial cell or virus
-Killer cells or inactive viruses- dead
-Live, attenuated cells or viruses- softened
Antigenic molecules derived from bacterial cells or viruses |
Whole bacterial cells or virus: Dead | dead organisms are safest
less effective immunogens
wrong POE (portal of entry) |
Whole bacterial cells or virus: Live | live organisms offer better response
mimic actual infection
mutate back to virulent form |