Immunology specific host defense Flashcards
Immune system: two part
- Humoral Immune system
2. Cellular immune system
Humoral Immune System
Involves a specific antibodies in the blood and lymph (the body’s humors) Produced by B CELLS
Cellular Immune system
Involves T CELLS. That do not produce antibodies but secretes cytokines.
Specialized lymphocytes responses to
Extracellular ags
T cells mature in the
Thymus
After maturation, T cell migrate to
Lymphoid tissues
7 types of immunity
- Innate Immunity
- acquired immunity
- Natural acquired ACTIVE immunity
- Artificially acquired ACTIVE immunity
- Passive immunity
- Natural acquired PASSIVE immunity
- Artificially acquired PASSIVE immunity
Innate Immunity
Born with it
Acquired Immunity
Adaptive immunity
Resistance to infection due to ANTIBODIES
a. Active immunity (made by yourself)
b Passive immunity (performed by someone else)
Natural acquired active immunity
Person making their own antibodies
1. stimulus: Contact with the live microbes by Natural Process - infection; illness
2. Responses: Symptoms of disease or subclinical RXN. Active production of antibodies to the pathogen
Duration: Long term (months-years) sometimes life long. ex: Influenza.
Artificially acquired active immunity
Antigen is intentionally introduced to the body (vaccine.immunization)
- Stimulus: Vaccines/ Immunization:
a. Kill pathogens (or their proteins alone)
b. Attenuated/weaken live pathogen
c. Inactivated toxin (TOXOID) - old, resembling toxoid will cause immune response. - Response: Production of specific antibodies without developing symptoms of disease (or prodromal symptoms only)
- Duration: Variable (months-years-life time)
Passive Immunity
Immunity acquired through transfer of antibodies.
Naturally acquired Passive immunity
- Mother to fetus through the placenta (Placental transfer) or in colostrum/milk during nursing.
- Response: No immune response. Acquisition of antibody only.
- Duration: short term (a few weeks - months)
Artificially acquired passive immunity
- Antibodies formed in one individual transferred/injected into another individual. Immune serum/gamma globulin.
- Response: No immune response, acquisition of antibody only.
- Duration: Very short (2-3 weeks) e.g. Venomous snakes bites, tetanus, Hep. A, Diphtheria, Botulism.
Specific immune response involves production of ______ antibodies (Ab) against specific antigen (Ag).
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The Nature of Antigens/Immunogens Definition
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The Nature of antigen/Immunogen: Characteristics
FOREIGN/NON Self Matter eg. Microorgamism, toxins, Foreign tissues.
Chemically: Complex Molecules: Eg. Protein or Polysaccharide
The more complex the better
Hapten/Partial Antigen
Has reactivity (combines with specific antibody) without immunogenicity (stimulating production of specific antibodies) unless bound to a carrier.
Antigenic determinant epitope
Antibodied are not formed against a whole organism but specific regoins or chemical groups
Nature of antibodied/immunoglobulins
Definition: A protein produced by B lymphocytes in response to an immunogen/antigen and is capable of combing with that antigen.
Gamma Globulins:
From separation of blood proteins by electrophoresis
Concerts artificial acquired passive immunity
Antibody Structure
Two heavy chains and two light chains. Heavy and light chains both have C or constant portion and the V or variable portion.
V portion:
Is different for each kind of Ab and gives ab its specificity. Ag binding occurs at the V portion.
C portion:
Constant for each class of ab.
Fab
Antigen binding fragament: the two arms
Fc:
Crystallizable fragement: the “trunk” of the antibodies. Contains the complement binding site.
5 Classes of antibodies
IgG IgM IgA IgD IgE
IgG
Monomer 80% of serum antibodies
(most abunant ab in Serum)
can cross the placenta **Pretects fetus and newborn
Fix complemen. Enhance phagocytosisl neutralize toxins and virus,
IgM
Pentamer 5-10% of serum antibodies
Fixes complement in blood, lymph, on B cells
Agglutinate microbes; also Ab produced in response to infection
IgA
Dimer 10-15% of serum antibodies main ab in mucus secretion, and breast milk.
mucosal protection
igD
Monomer 0.2% of serum antibodies in blood and lymph. Receptor on B cells
IgE
Monomer 0.002% of serum antibodies.
on mast cells and basophils, in blood.
Allergic reaction; lysis of parasitic worm
Antibody responses (B cells)
1st response: contact with the Ag for the first time.
-plasma cells -> antibodies
- Memory cells are formed - has specific receptors
2nd response/anamnestic(memory) response
- Memory cells activated -> plasma cells -> antibodies formed quickly and in large number
Cell mediated immunity
Involves interaction of macrophages and specific T lymphocytes (T-cells)
Pathogens enter the gastrointestinal or respiratory tracts pass through peyer’s patches, which contain APCs (antigen-presenting cells)
Dendritic cells
M (Microfold) cells over Peyer’s patches facilitate contact of antigens with the immune system.
T-cells differentiate into _____ T cells when stimulated by an antigen.
effector
Some effector T-cells become memory cells
T cell types
Helper T cell (CD4, Th) Th1 Th2 Cytotoxin T cell Delayed hypersensitivity T cell Suppressor T cell
Th1
Activate cells related to cell-mediated immunity
Th2
Activate B cells to produce IgM and igE
Cytotoxic T cells (CD8,Tc)
Destroy target cells with perforin
Delayed hypersensitivity t cell
Td: Associated with allergic reaction, transplant rejection, and tuberculin skin test
Suppressor Tcells
ts: turns off immune response when antigen is no longer present.
Also called regulator t cells
Nonspecific cells
Activated macrophages Natural killer cells T-dependent Antigens T-Independent Antigen Antibody-dependent Cell-mediated Cytotoxicity Self Tolerate Clonal deletion Major Histocompatibility complex Human leukocyte Antigen complex
Activated Macrophages
Macrophages stimulated by injection of antigen or by cytokines
Natural killer cells
lymphocytes that destroy virus-infected cells, and tumors
Same function of cytotoxic Tcells but nonspecfic - clumsy. A lot of collateral damage.
T-dependent antigen
Sequence of event t cell comes before b cells (plasma memory)
T-independent antigen
limitation: has to be a large molecule but B cell can replicate without Tcell
Antibody dependent cell mediated cytotoxicity
Read page 485
Self tolerant
The immune system does not normally attack self tissues or compounds.
Clonal deletion
During embryonic development lymphocytes with antigen receptors for molecules present in the body are destroyed (theory)
Major Histocompatibility complex
(MHC) or other wise known as Human Lekocyte Antigen complex (HEA)
Glycoproteins in plasma membrane the enable the immune system to distinguish self from nonself.
Class I MHC: On all nucleated cells (almost all your cells)
Class II MHC: On macrophages and B cell.