Immunology -Vishy Flashcards
What are the layers of the epidermis from outermost–> innermost?
Stratum Corneum Stratum Lucidum Stratum granulosum Stratum spinosum Stratum basale
Where is Dsg1 found in the epidermis? What about Dsg 3? What diseases are associated with autoantibodies produced against these?
- Dsg3 is in the deep epidermis–> pemphis vulgaris (IgG)
- Dsg 1 is more in the superficial epidermis–> pemphis (IgG)
What is filaggrin responsible for? What results from a mutation in filaggrin?
fillaggrin is responsible for the terminal differentiation of the epidermis
-a mutation in fillagrin leaves the body more susceptible to bacterial and hypersensitivity reactions (atopic dermatitis)
What are the immune cells of the epidermis called? What is their function?
langerhans cells
-antigen presenting cells that phagocytose and pinocytose material to conjugate with MHC I or II and then enter lymphatic circulation to present to T cells
How are extracellular antigens processed for T cell recognition?
Extracellular anitgens –> endosome–> paired with MHC class II –> presented to CD4+T cells for recognition
How are intracellular antigens processed for T cell recognition?
Intracellular–> proteosome compartment –> antigenic peptide –> RER using TAP (transporter protein)
-conjugated with MHC I in the ER –> recognized by CD8 T cells
How many signals are required an antigen presenting cells to stimulate T cell proliferation?
2 signals:
1=Class II MHC on APC + TCR on T cell
2=
- ICAM-1 on APC presenting to LFA-1 on T cells
- B7-1/B7-2 on APC presenting to CD 28 on T cell
What happens after full activation of T cells? What can a person get if this does not occur?
after full activation, CD28 will disappear and CTLA 4 will appear.
- CTLA-4 will bind CD80/86 and inactivate the immune cells
- without inactivation, can get autoimmunity
What do Th1 cells secrete? Th2 cells? What are their functions?
Th1 cells secrete IL-2 and IFN-gamma –> important in neutophil and macrophages activation
Th2 cells secrete IL-4, IL-6 and IL-10. These stimulate B cells to produce certain classes of antibodies
What cytokines stimulates a T cell to exhibit a Th1 cell response? What cytokine stimulates a Th2 response?
IL-12 stimulates Th1
IL-10 stimulates Th2
What receptor is found on both basophil and mast cells? What does this bind to? Where are basophils and mast cells found?
Fc receptors on their surfaces bind to IgE
basophils are found in low numbers in the blood
Mast cells are in the dermis
What happens during the initial allergen encounter with an antigen? Subsequent allergen encounters?
- initial encounter: CD4 –> Th2 –> IL4 and IL5 produced ==> mast cells coated with IgE (bound by the Fc receptors)
subsequent: cross-linking of antigen to IgE on mast cells causes mast cell degranulation that releases vasoactive amines, cytokines, lipids
What types of physiological responses take place with a type I hypersensitivity reaction?
- constriction of bronchiole lumen
- vasoconstriction of the blood vessels
- endothelial vasodilation –> fluid loss and cell migration which causes urticaria
What are the 2 phases of atopic dermatitis? W T cell predominates in each phase? What type of infection is a person with more susceptible to in each phase?
acute:
- Th2 predominates–> produce IL4 and IL5. DCs produce IL-10.
- IgE and allergic reaction
- No INF gamma production=susceptible to bacterial infection of the skin
chronic
- CD4 Th1 predominates
- DCs produce IL12–> Th1 –> INF gamma produced (less susceptible to bacteria)
- Less plasmacytoid DCs=more susceptible to viral infections (less INF alpha and beta)
What molecule on T cells allow them to leave circulation and go to the skin? Where can these be found in atopic dermatitis?
CLA (cutaneous lymphocyte associated antigen)
can be detected in the dermis and epidermis