Host defense Flashcards
What are the five types of pathogens that can invade the body?
- Extracellular bacteria
- Intracellular bacteria
- viruses
- Fungi
- Parasites
In addition to invading the host, causing damage, and colonizing, what must a microbe do to cause disease?
Evade the immune system
Why would an antibody response to an intravellular bacteria be ineffective?
Antibodies cannot penetrate cells
What are the two major mechanisms by which extracellular bacteria mediate tissue damage?
Generate inflammation
Release toxins
What is the first line of defense against invading microbes
Phagocytosis
What are the two ways in which complement can act to aid in the destruction of microbes?
Opsonize
Directly lyse
What is the component of the bacteria cell wall in gram positive bacteria? Gram negative?
Gram positive = peptidoglycan
Gram negative = lipopolysaccharide
What is the principle protective response (protects against developing the disease at all)?
Humoral immunity
Which class of antibodies opsonize microbes?
IgG
What are the two types of antibodies that can activate the complement pathway?
IgM and IgG
Which is the antibody that is found in the primary reaction? Secondary?
Primary = IgM Secondary = IgG
What is the chemical secreted by helper T cells that assist in B cell-mediated humoral immunity, and is the most potent activator of macrophages?
interferon-gamma.
What is the effect of the bacteria polysaccharide capsule that some bacteria are able to produce?
Resist phagocytosis and may inhibit complement activation
What is the effect of genetic variation seen in the surface antigens of bacteria?
Constantly change targets
What is the bacteria type that mediates septic shock?
Gram negative
What are the cytokines release by the body that induce septic shock?
IL-1 and TNF
What are superantigens?
Toxins that bind to class II MHC proteins, and activate T cells to produce TNF
What are the genes that an individual must express in order to be susceptible to superantigens?
V[alpha] or V[beta] regions in the variable chain of the TCR
What causes the carditis seen in rheumatic fever?
Cross reactive antibodies
What else besides carditis can rheumatic fever cause? What causes this?
Poststreptococcal glomerulo-nephritis, caused by immune complexes lodging in the kidneys