immunology Flashcards
1
Q
CD4+ T cell activation
A
- signal 1: MHCII presents antigen to CD4+
- signal 2: B7 on APC binds CD28 on CD4+
- activated CD4+ cell divided into 2 subesets: TH1 and TH2
- TH1: secretes IFN-gamma – activiates macros and CTL –> kill intracell organisms (cell-mediated immunity)
- TH2: secrete IL-4, IL-5, IL-6, IL-13 –> recruits eosinophils for parasite defense and promotes IgE production by B cells (humoral immunity)
2
Q
CD8+ T cell activation
A
- signal 1: MHC I presentation to CD8+ cell
- signal 2: IL-2 from CD4+ TH1 cell
- CTL kill virus-infected cell, neoplastic and donor graft cells by inducing apoptosis
- CTL secrete perforin and granzyme –> perforin creates pore for granzyme to enter cell and activate apoptosis
3
Q
B cell activation
A
- Helper T cell activation: B cell antigen presentation to CD4+ T cell via MHCII (signal 1)
- CD40 receptor on B cell binds CD40L on helper T cell (signal 2)
- Helper T cell then secrete IL4 and IL5 to mediate B-cell class switching, affinity maturation and Ab production
4
Q
IgA
A
- prevents attachment of bacteria and viruses to mucous membranes
- released into secretions and breast milk
5
Q
IgG
A
- main Ab in delayed response to Ag
- fixes complement, crosses the placenta, opsonizes bacteria, neutralizes bacterial toxins and viruses
6
Q
IgM
A
- produced in immediate response to Ag
- fixes complement
- monomer on B cells or pentamer when secreted
7
Q
IgD
A
- mature B lymphocytes epxress IgM and IgD on their surfaces –> differentiate in germinal centers of LNs by isotype switching (mediated by cytokines and CD40L) into plasma cells that secrete IgA, IgE or IgG
8
Q
IgE
A
- binds mast cells and basophils –> cross-links when exposed to allergen –> type I hypersensitivity
9
Q
complement overview
A
- innate immunity
- Classic pathway- C1 binds IgG or IgM that is bound to Ag (GM makes classic cars)
- Alternative pathway- microbial products directly activate complement
- Mannose-binding lectin pway- activated by mannose on microbe surface
- all result in production of C3 convertase –> C3a and C3b –> C5 convertase –> C5a and C5b –> C6-9 –> MAC
- C3a, C4a and C5a = anaphylatoxins –> mast cell degranulation, HA-mediated vasodilation and increased permeability
- C5a also chemotactic for neutrophils
- C3b binds bacteria (opsonin for phagocytosis)
- C3b and IgG are the 2 primary opsonins in bacterial defense
10
Q
IL-1 through IL-6
A
- IL-1: fever (hot)
- IL-2: stimulates T cells
- IL-3: stimulates Bone marrow
- IL-4: stimulates IgE production
- IL-5: stimulates IgA production
- IL-6: simtulates aKute-phase protein production
all secreted by macros
“Hot T-bone stEAK”
11
Q
IL-8
A
- secreted by macros
- major chemotactic factor for neutrophils
“clean up on aisle 8!”
12
Q
IL-12
A
- secreted by macros
- induces differentiation of T cells into Th1 cells
- activates NK cells
- also secreted by B cells
13
Q
TNF-alpha
A
- secreted by macros
- mediates septic shock
- activates endothelium
- causes leukocyte recruitment and vascular leak
14
Q
interferon alpha and beta
A
- innate host defense against RNA and DNA viruses
- glycoproteins synthesized by virally infected cells to warn neighboring cells and prime them for viral defense
- when a virus infects a primed cell they undergoapoptosis –> interrupts viral amplification
15
Q
B and T cell markers
A
- B cells: 19,20,21
- T cells: 3, 4(TH cells), 8 (CTL)
