Hypersensitivity reactions Flashcards
1
Q
What are the types of hypersensitivity reactions?
A
Type I:
- Involve IgE antibodies which provokes an inflammatory response upon subsequent exposure to an allergen.
- Allergies and hay fever are both type I.
Type II
- Cytotoxic
- Hypersensitivities involving the binding of IgG and IgM antibodies to antigens on cell surfaces which leads to apoptosis
- Hemolytic transfusion reactions and hemolytic disease of newborns are type II reactions.
Type III:
- Result from the formation of antigen-antibody complexes that settle on tissues and organs.
- Rheumatoid arthritis
Type IV
- Hypersensitivities are regulated by T cells and are delayed reactions to antigens associated with cells
- Tuberculin reactions, chronic asthma
2
Q
What are the roles of gingipains in periodontal hypersensitivities?
A
- Gingipains: consist of an enzymatic part and a body. The enzymatic part degrades proteins
- The gingipain will inhibit IFN-Y (which would otherwise have worked to stable the periodontal lesion)
- They also disrupt neutrophils
- Macrophages recognize the enzymatically active gingipain and inactivate it
- While the inactive gingipain is readily taken up by the macrophage it is not recognized and remains distributed throughout the cytoplasm
- High levels of gingipains kill the macrophage
- Unfortunately, in diseased periodontal sites there is poor recruitment and activation of macrophages
- This shows the failure of the immune response; the immune response becomes corrupted by the microbial insult
