t cells Flashcards
tell me the life story of t cells
born in the bone marrow and migrate to thymus as thymocytes, there they become mature t cells then travel to periphery lymph organs and wheras memory t cells reside in the blood stream until directed to enter tissue to elicit immune response
what are three types of t helper cells and what do they do
Th1 cell mediated immunity IgG, Th2 Humoral immunity IgE, Th17 enhances inflammation
what type of t cell lyse virus infected cells
cytotoxic t lymphocytes
name two regulatory t lymphocytes
Th3 cell and T reg
what is the TCR
The T Cell antigen Receptor is the proteins on the surface of the t cell that interact with MHC 30000 copies per cell
what is the composition of a TCR
Di-sulphide linked A and B chains similar to antibodies, have constant and variable regions as well.
what are the characteristics of the TCR
trans membrane portion not long enough to conduct signal, bind both MHC and antigen on both units, never secreted and only one bidnding site.
what helps the TCR conduct the signal across the membrane of the t cell
CD3
what are the components of the CD3 and where is it phosphoralated
one Gamma one Delta two Epsilon and a Zeta chain, and the site of phosphoralation is on the cytoplasmic tails for transduction.
what are co stimulatory molecules and name some
they are needed to elicit a t cell response, examples are CD28 binds to B7, CD40 Binds CD 40L…B7 and CD40 are found on all APC
what are the characteristics and functions of CD4
monomer glycoprotien, found on most APC and 65 percent of mature t cells. Helps with adhesion transduction and restriction
what are the characteristics and functions of CD8
homodimer or heterodimer, expressed on cytotoxic T cells. Cell adhesion transduction and restriction.
what are the early activation events in signal transduction
phosphoinositide pathways activated and protein kinase c and other kinases phosphorylated transcription factors
what two events occur due to signal transduction
cell proliferation genes are transcibed interluekin 2 and IL2 receptors for growth, and mitosis to expand immune response
how do Th0 cells diffentiate into Th1 and Th2 cells
if interluekin 12 is present they will become Th1 and if interleukin 4 is present they will become Th2. If IL12 is not present it will default to Th2 cells
what produces IL12 and IL4
mast cells make IL4 or antigen activated T cells, whereas macrophages or activated dendritic cells produce IL12
what other factors play a role in diffenation of Th1 or Th2
lots of peptides make Th1 small peptides Th2 strong peptide bonding to t cells makes Th1 and loose binding is Th2
what type of cytokin does Th1 cells produce
interferon gamma and IL2. Interferon makes B cells make IgG and Il2 makes cytotoxic t cell to kill virus infected and intracellular bacteria
what type of cytokin does Th2 cells produce
IgE antiboides and mast cell mediated immune reaction against helmith (worm) infestation
how are cytotoxic t cells CTL activated
Class 1 MCH with co stimulatory molecules CD40 and CD28 makes IL2 and interferon Gamma
how do CTL kill other cells
deliver perforins that target cell surface causing lysis, granzyme b activates caspases cascade, or fas protein for caspase and apoptosis.
what are gamma delta t cells
no CD4 or CD8 but yes to CD3. Found in intestinal intraepithieial t cells, limited TCR diversity, might recognize antigens directly heat shock protiens ect..
what are NKT Cells
located in thymus and lymphoid organs invariant alpha chain with one of three beta chains, antigens for glycolipids secrete Il4 IL10 and INF gamma
