Lecture 11 Flashcards
What is the adaptive immunity?
defenses that target a specific pathogen
What is the primary and secondary response for adaptive immunity?
- primary: first time the immune system combats a particular foreign substance
- secondary: later interactions with the same foreign substance; faster and more effective due to memory
What are the 2 types of immunity?
1) humoral immunity
2) cellular immunity (cell-mediated immunity)
What is humoral immunity?
produces antibodies that combat foreign molecules (antigens)
What are b cells? What type of immunity are they involved in?
- lymphocytes that are created and mature in red bone marrow
- recognize antigens and makes antibodies
- humoral immunity
What are cytokines?
chemical messengers produced in response to a stimulus
What are interleukins? (ILs)
cytokines between leukocytes
What are chemokines?
induce migration of leukocytes
What are interferons? (IFNs)
interfere with viral infections of host cells
What are tumor necrosis factor alpha? (TNF-alpha)
involved in the inflammation of autoimmune diseases
What are hematopoietic cytokines?
control stem cells that develop into red and white blood cells
What does overproduction of cytokines lead to?
cytokine storm
What are antigens?
substance that triggers an immune response by being recognized as foreign by the immune system
- substance that cause the production of antibodies
What is an antibody?
protein produced by the immune system (by B cells) in response to an antigen, designed to bind to and neutralize or mark the antigen for destruction
What do antibodies interact with?
epitopes, antigenic determinants
- on the antigen
What are haptens?
antigens too small to provoke immune responses and attach to carrier molecules
What are immunoglobulins? (Ig)
globular proteins
What does valence mean in antibodies?
number of antigen-binding sites on an antibody
What does a 4-protein antibody chain look like?
2 identical light chains + 2 identical heavy chains joined by disulfide links
- variable regions at the ends of the arms to bind epitopes
- constant region is the stem (identical for a particular Ig class)
What are the characteristics of IgG?
- monomer
- 80% serum antibodies
- in the blood, lymph, intestine
What are the functions of IgG?
- crosses the placenta
- protect the fetus
- triggers complement
- enhances phagocytosis
- neutralizes toxins and viruses
What are the characteristics of IgM?
- pentamer made of five monomers held with a J chain
- 6% of serum antibodies
- remains in blood vessels
- first response to an infection, short-lived
What is the function of IgM?
causes clumping of cells and viruses
What are the characteristics of IgA?
- monomer in serum
- dimer in secretions
- 13% of serum antibodies
- common in mucous membranes, saliva, tears, and breast milk
What is the function of IgA?
prevents microbial attachment to mucous membranes
What are the characteristics of IgD?
- monomer
- 0.02% of serum antibodies
- structure similar to IgG
- in blood, in lymph, and on B cells
What is the function of IgD?
- no well-defined function
- assists in the immune response on B cells
What are the characteristics of IgE?
- monomer
- 0.002% of serum antibodies
- on mast cells, on basophils, in blood
What is the function of IgE?
cause the release of histamines when bound to antigens
- lysis of parasitic worms
What is the function of the major histocompatibility complex?
- the genes encode molecules on the cell surface
- Class 1: membrane of nucleated animal cells
- Class 2: surface of antigen-presenting cells (also B cells)
How do antibody-producing cells go through clonal expansion?
- inactive b cells contain surface Ig that bind to antigen
- B cell internalizes and processes antigen
- antigen fragments are displayed on MHC class II molecules
- T helper cell contacts the displayed antigen fragment and releases cytokines that active B cells
- B cell undergoes proliferation
What does clonal selection differentiate activated B cells into?
- antibody-producing plasma cells
- memory cells
What is clonal deletion?
eliminates harmful B cells
What are t-dependent antigens?
antigen that requires a helper-T cell to produce antibodies
What do t-independent antigens do?
- stimulates B cell without the help of T cells
- provokes a weak immune response to produce IgM
- no memory cells generated
What are the results of the antigen-antibody interaction?
- antigen-antibody complex forms
- protects the host by tagging foreign molecules or cells for destruction
= agglutination
= opsonization
= antibody-dependent cell-mediated cytotoxicity
= neutralization
= activation of the complement system
What is affinity?
strength of the bonds
