principles of immunology t cell-mediated immunity 3/28/06 “each of us needs to be the change we...
TRANSCRIPT
Principles of Immunology
T Cell-Mediated Immunity3/28/06
“Each of us needs to be the change we wish to see in the world”
Ghandi
Word/Terms List
ADCC Effector cells GVH reaction Perforin
T Cell-mediated Immunity
Principal function-Response to intracellular pathogens and cells expressing foreign antigensRecirculation-Naïve T cells circulate
between the blood stream and the lymphatic system
Antigen presentation-Naïve T cell cells only respond to APCs
Priming of T Cells
Three types of effector T cells CD8 (TC) CD4 (TH1) CD4 (TH2)
Each type Responds to different types of Ags Activated by different Ag presentation Has different effector function
T Cell Effector Types CD8
Viruses and intracellular bacteria MHC I Cytotoxic effector cells
CD4 TH1 Bacteria and parasites in APCs MHC II Effectors activate macrophages, CTLs and induce B cells to
produce opsonins
CD4 TH2 Extracellular bacteria and toxin producers MHC II Activate B cells to produce multiple antibody classes
T Cell Adhesion
T cells pass through endothelial cells (extravasation)
Endothelial cells and T cells both have cell adhesion molecules (CAMs)
Various CAMs
Cell Adhesion Molecules
Selectins
Mucins
Integrins
Immunoglobulin superfamily
APCs
Dendritic cells
Macrophages
B cells
Dendritic Cells
Antigen presentation is sole function Antigenic uptake is followed by
migration to lymph nodes Expression of MHC I, MHC II and B7 Loses phagocytic property Secretes chemokines
Macrophages
Involved in both innate and adaptive immunity
May destroy pathogens or present Ag to T cells
Expression of MHC I, MHC II and B7 Scavenges dead cells
B Cells
Binds soluble antigens
Constitutively expresses MHC II
Induced to express B7
NK Cells
~5% of lymphocytes Nonspecific cytotoxicity No TCR/CD3 Not MHC restricted No memory
CTL Cytotoxicity
Conjugate formation Membrane attack Dissociation Target cell death
Conjugate Formation
Cell adhesion Recognition of MHC I:Ag on target cell
Membrane Attack
Granules in CTLs Perforin Granzymes
Exocytosis of granule contents Perforin action similar to C9 Granzymes act as nucleases
Fas ligand to Fas triggers target cell death
Dissociation and Target Cell Death
CTL interacts for about five minutes Dissociates and can conjugate with
other target cells Target dies after several hours
Antibody-Dependent Cell-Mediated Cytotoxicity
NK cells, macrophages, neutrophils Bind to Fc region of Ab Multiple cytotoxic mechanisms
Graft vs. Host Reaction
Immunocompromised recipient Lymphocytes of donor attack
allogeneic antigens of recipient Splenomegaly