24 - Immune System in Action Flashcards
Pathogencity, Leprosy, Immunodeficiency, Immune Response, Sensitivity, Autoimmune Diseases
Pathogenicity
Mechanisms of tissue damage by pathogens can be divided into 2 groups…
DIRECT and INDIRECT effects
Give 3 examples of direct mechanisms of tissue damage…
- Exotoxins
- Endotoxins
- Direct cytopathic effect
Give 3 examples of indirect mechanisms of tissue damage…
- Immune complexes
- Anti-host antibodies
- Cell-mediated immunity
Indirect tissue damage is damage as a result of the…
Immune system
Immune complexes
Clumps of antibodies bound to soluble antigens, which effectively become antigens themselves
Leprosy is caused by the bacteria…
Mycobacterium leprae
Distinguish between the two different clinical forms of leprosy…
-
Tuberculoid leprosy
- Organisms present at low-undetectable levels
- Low infectivity
- Granulomas and local inflamation, peripheral nerve damage
- Normal serum Ig
- Normal T cell responsiveness (specific respone to M. leprae antigens)
-
Lepromatous leprosy
- Organisms show reddish growth in macrophages
- High infectivity
- Infection spreads - bone, cartilage and diffuse nerve damage
- Hypergammaglobulinemia
- Low or no T-cell responsiveness (no response to M. leprae antigens)
Immunodeficiency can be either…
Primary (caused by an intrinsic genetic defect) or secondary (from an environmental cause)
Primary immunodeficiency is ( rarer / more common ) than secondary.
Primary immunodeficiency is rarer than secondary.
List 5 factors linked to secondary immunodeficiencies…
- Malnutritiion
- Lymphoproliferative disease
- Immunosuppressive or cytotoxic drugs
- Infections (such as measles or HIV)
- Stress
List 5 types of immunodeficiency…
- Severe combined immunodeficiency
- X-linked agamma-globulinaemia
- NK cell defect
- IgA defect
- MHC class I deficiency
For the following 5 types of immunodeficiency state the functional consequence and the resulting susceptibility…
- Severe combined immunodeficiency
- X-linked agamma-globulinaemia
- NK cell defect
- IgA defect
- MHC class I deficiency
- Severe combined immunodeficiency -> No T or B cells -> General
- X-linked agamma-globulinaemia -> No B cells or antibodies -> Extracellular bacteria, viruses
- NK cell defect -> no functional NK cells -> Herpes viruses
- IgA defect -> No IgA -> respiratory infections
- MHC class I deficiency -> No CD8 T cells -> Viruses
Describe and contrast the primary and secondary immune responses, in terms of antibody production over time…
- Primary response - initial lag phase, followed by production antibodies.
- Secondary response - faster response of greater magnitude
Immunopathology - hypersensitivity reactions
Describe the difference between types I-III versus type IV hypersensitivity reactions…
Types I-III are antibody mediated whereas type IV is cell mediated (delayed-type hypersensitivity reaction)
Outline the Type I hypersensitivity reaction…
- Allergic reaction
- Involves IgE
- Mast cell activation -> granule release
- Need for cross linking ensures appropriate magnitude of response
- Severe cases = anaphylaxis
