L18-Immunology (28) Flashcards
http://www.youtube.com/watch?v=h5oOUMP4_UM Immune response-Bacterial Infections
Describe the development of different types of leukocytes.
Bone marrow stem cell can become myeloid (innate) or lymphoid (active) precursor. Myeloid can become monocytes (APCS-dendritic or macrophage) or granulocytes (neutrophil or mast). Lymphoid can become T cell (thymus) or B cell (bone marrow), which can later become a plasma cell.
Define: MHC.
Assists in antigen presentation. Every host cell has major histocompatibility complex proteins (MHC) and antigen presenting cells have MHC II.
Describe innate immunity.
- nonspecific
- does not require previous exposure to pathogen
- mediated by phagocytes, PRR bind to PAMPs, use cytokines to recruit more phagocytes
- recruit other immune cells for adaptive immunity
Define: PRR, PAM.
pattern recognition receptors and pathogen-associated molecular patterns.
Phagocytes have pattern recognition receptors (PRRs) on cell membrane. When PRR interact with a pathogen-associated molecular pattern (PAMP), phagocytosis is activated.
What is the adaptive immune response?
- acquired ability to recognize and destroy an individual pathogen (antigen-specific)
- pathogen specific receptors are produced AFTER exposure to pathogen or its product
Explain the process of antigen presentation to T cells.
1) Phagocytosis of the pathogen
2) presents antigen (part of digested pathogen) on MHC I and II
3) T-cell receptors TCR interact with MHC and antigen
4) Leads to T-cytotoxic produce perforin/granzymes to lyse nearby target cell or CD4 T-helper produce cytokines to activate other cells, inflammation.
Describe antibody structure and function.
- soluble protein made by B and plasma cells
- binds to a specific antigen and marks for destruction
- can also block interactions between pathogens or their products and host cells (neutralization)
At the molecular level, what cause the wide diversity of antibodies?
- V(D)J-variable, diverse, joining recombination
- heavy and light chains have constant and variable chains encoded by genes on 3 loci
- VDJ portions randomly recombined for heavy chains
- VJ portions randomly recombined for light chains
How are pathogens targeted for destruction by antibodies?
1) Antibodies binds to a specific antigen.
2) Complement (group of proteins) attach to pathogen surfaces and create pores for lysis or block pathogen toxins/interactions
3) neutrophil/macrophage Fc receptors bind antibodies or complement to enhance phagocytosis (opsonization)
List the different types of immunoglobulins and their function.
IgE-immediate hypersensitivity allergies, parasite immunity (bound to mast cells)
IgA-mucosal immunity (serum/mucus secretions)
IgG-(serum) secondary
IgM-(serum) primary
What is immunological memory and how is it created?
defn-creation of database of antibodies for mounting larger secondary responses after antigen reexposure
1) B cells (preformed antibodies), bind antigens using Ig.s,
2) presents antigens to TH2 cells.
3) TH2 cells produce cytokines to stimulate growth of B cells into plasma cells
4) plasma cells produce antibodies.
What is the purpose of inflammation in the immune response?
rapid localization and destruction of the pathogen by macrophages and recruited neutrophils
Define: tolerance and autoimmunity.
- tolerance: acquired inability to produce an immune response to a specific antigen
- autoimmunity-T cells and B cells react with self antigens (normally eliminated during process of lymphocyte maturation), lead to disease
Describe the difference between active and passive immunity. Give examples of each.
active-exposure to antigen through infection, protective immunity ex. common cold, natural infection
passive-non-immune, person’s acquisition of preformed immune cells or antibodies via natural transfer ex. IgG antibodies through placenta, IgA from breast milk
How do super antigens work?
activate more than normal 20-25% T cells via non-specific binding of antigen, Ex. Staph aureus food poisoning and Strep pyogenes scarlet fever
