11: Immunity And Hypersensitivity Flashcards
What do IL-4, IL-5, and IL-13 do in Type I hypersensitivity?
IL-4: IgE class switching
IL-5: eosinophil activation
IL-13: enhance IgE activation
Paracortex vs germinal centers of LNs
Paracortex: mostly T cells
Germinal centers: mostly B cells
MHC class I vs class II - which cell types and what they display
Class I: all nucleated cells, display cytoplasmic Ags (viral, tumor)
Class II: APCs, display extracellular Ags (bacterial, allergens)
Ag processing for MHC class I vs class II
Class I: proteasome forms peptides from Ag -> into ER -> load into MHC -> entire complex migrates to surface
Class II: Endolysosomal enzymes form peptides from Ag -> vesicles form with peptide and complex -> migrates to surface
Which T cells recognize which MHCs?
CD4: MHC II
CD8: MHC I
Response to MHC I recognition vs MHC II
MHC I: killing of Intracellular pathogens
MHC II: recruitsment of macrophages and other T cells
What does the heterogeneity of HLA haplotypes mean?
Differences in fighting illnesses, differences in allergic sensitivities
Clonal selection and deletion
Selection: after Ag introduction, the particular lymphocyte produces identical cells
Deletion: lymphocytes are killed if they recognize self Ags
Three things possibly indicated if a large population of B or T cells has the exact same genes?
- Abnormal clones
- Neoplasia
- Lymphoma
Hypersensitivity reaction
Immune reaction to a foreign or self Ag that is excessive and/or harmful
How does the skin-prick test work for Type I Hypersensitivity
- Allergen binds IgE bound to mast cells -> cross-linking activates mast cells
- Vasodilation, increased swelling and redness
Rheumatoid fever in the heart
Streptococcal Ag mimics myocardial Ag (molecular mimicry) -> cross reactive Abs to the heart
A hallmark of some type IV reactions including DM I
Granulomas
