Diebel Specific Acquired Immunity Flashcards
What causes naive lymphocyte to proliferate?
antigen binding
Describe humoral immunity:
B cells releasing antibody into tissue fluids, blood and secretions.
Describe cell-mediated immunity:
T-cells themselves survey the surface of the body’s cells, looking for ones that have parasites within them or that are dangerously changed or mutated.
MHC I is recognized by ______ T-cells?
CD8+ killers
MHC II is recognized by ______ T-cells?
CD4+ helpers
Another name for MHC molecules:
HLA (human leukocyte antigens)
Regions on an antigen that can be recognized by an antibody or by T-cell receptors:
Epitopes
Type of cytokine released by activated T-cells that have travelled to the site of infection:
lymphokines
An example of a lymphokine is INF-gama. What is its function at the infection site?
Stimulates M1 “angry” macrophages
Five subtypes of helper T-cells with CD4 molecular marker:
- Th1
- Th2
- Th17
- Tfh
- Treg
Cells that recognize antigen and produce lyphokines (INF-gama) to attract thousands of macrophages to wipe out infection or…
a transplanted kidney
Th1 (Type 1 helper T-cells)
Similar to Th1’s but more powerfull. Implicated in many serious forms of autoimmunity.
Th17
Type of cells that stimulate M2 macrophages
- promote healing
- important in parasite immunity
Th2
Cells stimulated by antigen and migrate from T-cell areas of lymph nodes to B-cell follicles
-help B-cells get activated to produce IgM, IgG, IgE, and IgA
Thf (Follicular helper T-cells)
Cells that make cytokines (IL-10) to suppress activation of Th1, Th2, and Th17
-keep immune response in check
Treg (Regulatory T-cells)
Cells that destroy any body cell they identify as bearing a foreign or abnormal antigen on its surface (MHC-I).
-have CD8 molecular marker
Cytotoxic or Killer T-cells
Describe T-cell activation via MHC-I APC:
Adhesion:
Ag-specific activation:
Co-stimulation:
Cytokine signals:
Adhesion: ICAM 1/3 (on APC) —- LFA-1 (T-cell)
Ag-specific activation: CD58 (APC) — CD2 (T-cell)
MHC I —- TCR
MHC I —- CD8
Co-stimulation: B7 (1 or 2) on APC —- CD28 (T-cell)
Cytokine signals: IL-1 (APC) —- IL-1R (T-cell) , paracrine
IL-2 (from other T-cells and self) —- CD25, autocrine/paracrine
How does activation of T-cells by APCs differ from MHC-1 to MHC-II?
Co-stimulation is with CD4 — MHC II instead of CD8— MHC I
Function of IL-2 and IL-15 with respect to T-cell activation:
general activators
Function of IL-12 and IFN-gama with respect to T-cell activation:
Drive T helpers to Th1 subtype
Function of IL-4 with respect to T-cell activation:
Drives helper cells to Th2 subtypes
Function of IL-10 with respect to T-helpers?
down regulates Th1
Function of TGF-beta with respect to T helpers?
down regulates both Th1 and Th2
Describe dendrite’s role in activation of T-cells:
- encounters antigen and engulfs it
- travels to spleen or lymph node while digesting antigen and presenting it on its surface in an MHC II molecule
- encounters and activates a T-cell which initiates full blown adaptive immunity
Two ways cytotoxic T-cells kill:
- FAS-FAS ligand interaction induces apoptosis in infected target cell
- by secreting toxic agents:
- TNF- can induce apoptosis
- Perforin- pore forming protein
- Granzymes- induce apoptosis
In negative selection of T-cells in the thymus, what happens if a T-cell recognizes “self” antigen on MHC II of the thymus epithelial cells?
they are driven to apoptosis and die
Cluster of differentiation markers present on T-cells:
CD3 (part of TCR complex)
CD4 or CD8
CD23
Cluster of differentiation markers present on B-cells:
CD1
CD19
CD20
CD23
CD40 (interact with Thf to progress to plasma cells)
CD79 (a and b) part of the BCR complex
Unlike T-cells which require MHC for activation, B-cells are activated by:
direct binding with antigen via antibodies
**now cell can differentiate and proliferate (usually with the help of Tfh)
Fully differentiated B-cell is called:
Plasma cell
-protein production factory for soluble antibodies
Five types of antibodies:
IgA
IgD (only on cell surface, not secreted)
IgG
IgE
IgM
Most abundant antibody in the body?
IgG
**can bind an antigen and activate complement
Only Ig that crosses placenta?
IgG
Large antibody that is the first to appear in blood after exposure to antigen?
IgM
**gets replaced by IgG after a week or two
Only real job of IgD?
B-cell membrane antigen binding receptor
Most important Ig in secretions like tears, saliva, GU, GI fluids, and milk?
IgA
What protects IgA from digestive enzymes?
Secretory component
Ig that attaches to Mast cells and causes production of leukotrienes, prosteglandins, and cytokines and release of histamine upon contact with an antigen?
IgE
Ig associated with resistance to parasites as well as allergic reactions:
IgE
Mucous membrane antibody?
IgA
Ig’s of deeper tissue like spleen and lymph nodes?
First IgM then later IgG
Hypersensitivity mediated by IgE:
**release of histamine by mast cells and basophils
Type 1
Hypersensitivity of autoimmune origin in which antibodies can react to self antigens (ie. hemolytic disease, myesthenia gravis, Goodpasture’s syndrome)?
Type II
Hypersensitivity caused by antibody/soluble antigen too small for phagocytosis so complement initiates usual inlflammatory response and tissue damage is caused?
Type III
ie. arthritis, SLE
Cell mediated hypersensitivity caused by T-cells?
Type IV
