Chapter 18: Adaptive Specific Host Denfenses

• Adaptive immunity


  Defined by 2 important characteristics: specificity & memory
• Specificity


  Refers to adaptive immune systems ability to target specific pathogens
• Memory


  Refers to its ability to quickly respond to pathogens to which is has previously been exposed

  *we get immunity from the memory because we have a way to remember how to fight off the disease
• Primary Response


  First exposure to a pathogen; happens after the primary immune response
• Secondary Response


  Any future exposures triggers this response

  *secondary response is faster and provides a much higher concentration of antibody

  *think of getting sneezed on for a second time and having already adapted to this strand that is going around
• Adaptive immunity involves two types of cells:

  B cells & T cells
• B cells


  mature in the bone marrow and produce glycoproteins called antibodies (immunoglobulins)

  *help defend against the extracellular environment
• T Cells


  Mature in the thymus and orchestrates innate and adaptive immune responses

  *play a role in destroying infected cells
• Antibodies=


  Humoral
• T cells=


  Actual cell in doing the immune activity
• Every antibody should have:

  Heavy chain= big piece (constant region)

  Lighter chain= smaller piece (variable region)
• What part of antibody binds to the epitope?

  variable region of the heavy and light chains
• Antigens


  *molecules that stimulate the production of antibodies

  *comes the combination of words: antibody and generator

  *Pathogen specific molecular structures

  *triggers the activation of the adaptive immune defenses
• Epitope


  Surface of antigens that antibodies recognize and bind to
• Haptens


  Small molecules not part of a larger molecule that can become antigenic when bound to a larger carrier molecule

  *often associated with allergic responses

  *have to bind to something to make it big enough to react with other molecules since it so small
• What shape are antibodies drawn as?


  Antibodies are always drawn like a Y
• Antibody


  A glycoprotein that acts against a specific antigen
• Immunoglobulin (ig) Classes


  IgG-immunoglobulin Gamma

  IgM-immunoglobulin Mu

  IgA-immunoglobulin (A refers to antibody)

  IgD-immunoglobulin Delta

  IgE- immunoglobulin Epsilon
• IgG (immunoglobulin gamma)


  Monomer

  *The antibody you produce when you are immune to something

  neutralises the antigen, fixes compliment

  high affinity due to maturation

  cant be secreted as it will be broken down by enzymes
• IgM (immunoglobulin Mu)


  Pentamer

  *FIRST RESPONDER >> 1st antibody produced during initial or primary response to an antigen / infection.

  This is the largest immunoglobulin by weight

  Found in blood and lymph fluid

  This is synthesized during fetal life >> Can have increased synthesis with infection in utero
• IgA (immunoglobulin A)


  Dimer

  *Neutralization and trapping of pathogens in mucucs
• IgD (Immunoglobulin Delta)


  Monomer

  *Limited information regarding precise function...

  VERY low concentration in adult serum

  May function as one type of B cell antigen receptor
• IgE (immunoglobulin Epsilon)


  Monomer

  *Least concentration in adult serum

  Found in mucus membranes, lungs, and skin

  MEDIATOR of many common allergic reactions >> Higher levels of this in people with allergies

  Crystalline fragment (Fc) binds to MAST cells

  Involved in defense against PARASITES!!!!
• Phagocytes


  macrophages and neutrophils and cells that can phagocytose
• Neutralization


  Binding of specific antigens found on bacteria viruses and toxins preventing them from attaching to target cells
• Opsonization


  process in the immune system where particles, such as pathogens or other foreign substances, are marked for ingestion and destruction by phagocytic cells, primarily macrophages and neutrophils.

  *process is crucial for the efficient removal of pathogens and other harmful substances from tissues and plays a central role in the body's defense against infections.
• Agglutination


  *process in which particles, such as cells or microorganisms, clump together to form aggregates.

  *used in microbiology, to detect the presence of specific antibodies or antigens.
• Phagolysosome


  lysosomes fuse with the phagosome

  *where antimicrobial chemicals and enzymes degrade the bacterial cell
• MHC 1


  Found on all healthy nucleated cells to signal to the immune system that the cell is a normal "self" cell
• T cells


  *cells develop from the same multipoint hematopoietic stem cells as other white blood cells

  *immature T lymphocytes then travel to the thymus for maturation

  *come from bone marrow 1st and then the thymus
• Bone Marrow


  *Red bone marrow can be found in head of femur, ilium and scapula

  *yellow bone marrow is populated primarily with adipose cells
• Thymus


  Gland in the thoracic cavity just above the heart where T lymphocytes mature.

  *helps remember the pathogen so you can fight it off faster
• Classes of T Cells

  Helper T cells, Regulatory T Cells, Cytotoxic T Cells
• Helper T Cells


  CD4; orchestrates humor and cellular immunity; involved in the activation of macrophages and NK cells

  *turn on the response
• Regulatory T Cells


  CD4; involved in peripheral tolerance and prevention and autoimmune responses

  *Says "ohh we are overreacting"
• Cytotoxic T Cells


  CD8; destroy cells infected with intracellular pathogens

  *knows the infected cells
• Subtypes of Helper T Cells

  Th1 Cells, Th2 Cells, Th17 Cells, Memory helper T Cells
• Th1 cells


  *stimulate cytotoxic T cells and produce cytotoxic T cells

  *stimulate macrophages and neutrophils for more effective intracellular killing of pathogens

  *stimulate NK cells to kill more effectively
• Th2 Cells


  -stimulate B cell activation and differentiation into plasma cells and memory B cells

  -direct antibody class switching in B cells
• Th17 Cells


  Stimulate immunity to specific infections such as chronic mucocutaneous infections