Glossary of Immunology lecture 04 Cell interaction molecules

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Why are cell interaction molecules generally call co-receptors?
Each molecule has a specific cell surface ligand and both cell surface molecules can transduce signals
Name two molecules that interact with the MHC
CD4 and CD8
Characteristics of CD4
Helper cells, ligand is MHC II, facilitates signal transduction in conjunction with the CD3 complex
Characteristics of CD8
Cytotoxic cells; ligand is MHC I; augements T cell activation by directly contributing to signal transduction
What does T cell LFA-1 (CD11a/CD18) bind to
ICAM-1 and ICAM-2 on the APC.
What does APC LFA-1 bind to
ICAM-3 on the T cell (DC-SIGN on dentritic cells)
When is LFA-1 important
Early stages of the immune response, greatly facilitating stabilization of T cell contact with APCs
What is Leukocyte Adhesion deficiency (LAD)
Immunodeficiency disease resulting from deficiency in LFA-1 or ligands for endothelial selectins
What is CD2
Single chain protein found primarily on T cells. Ligand is LFA-3. Functions to both mediate cell-cell adhesion and facilitate TCR signal transduction in conjunction with the CD3 complex
Where is CD 28 found
Primarily on T cells
What is the ligand for CD28
B7, expressed primarily on APCs
What does CD28 binding to its ligand accomplish
Results in generation of CD28 signals to the T cell, required for IL-2 production, T cell proliferation, and acquisition of T cell effector functions
What is the CD28 homologue and what does it do
CTLA-4; transmits negative signal to T cells, inhibiting their activation. Also binds B7; limits the amount of T cell proliferation and maintains tolerance to self antigens
Where is CD40 expressed
Activated B cells, dendritic cells, macrophages and thymic epithelium
Where is the CD40 ligand found
Activated CD4 cells, though it does not play a role in activation
What does CD40 binding to its ligand acheive
Helps mediate activation of B cells by T cells; also crucial for immunoglobulin class switching, resulting in production of IgG, IgA, and IgE
What is the immunological synapse
Formation of a stable interaction between the T cell and APC
What does the immunological synapse facilitate
Clustering of T cell receptors, as they engage peptide + MHC
What are supramolecular activation clusters (SMACS)
Cell surface molecules involved in the interaction at the IS
How are SMACS characterized
Central area consisting of the TCR, CD4, and CD28, surrounded by a ring of LFA-1 molecules
What are cytokines
Proteins that mediate immune responses, including inflammatory responses. Also mediate the development of cells associated with the immune response.
Name the three actions of cytokines
Autocrine, Paracrine, and Exocrine
What are the general groupings of cytokines based on function
Mediate hematopoiesis; mediate non-antigen specific immunity; mediate lymphocyte activation, growth, and differentiation; mediate effector cell activation; chemoattractants
How is the IL-2 receptor composed?
Three chains ,α β and γ. β has a low affinity for IL-2 without the help of the α chain. γ is bound to the β chain
What is Rapamycin
Immunosuppressive drug that functions by blocking transduction from the IL-2 receptor and other cytokine receptors
What causes septic shock
Endotoxin -stimulated overproduction of cytokines, including TNF-α and IL-1
What is the receptor for HIV
What is the receptor for the major rhinovirus serotype
ICAM-1. The virus competitively inhibits binding of LFA-1 to ICAM-1

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