#1 - Life of a T Cell: Forming and Educating the Army Flashcards
List the possible functions of the T cell (5)
1) Direct killing of infected cells
2) Release of cytokines that will recruit granulocytes, macrophages and monocytes
3) Assistance to B cells and the production of antibodies
4) Direct killing of self cells (pathogenic autoimmunity)
5) Vaccine response
when forming a new T cell, what is the order of chain construction? what domains contribute to the construction of the subunits?
Beta chain is assembled: this leads to pre-TCR, then alpha chain joins
beta chains are composed of all three (V,D,J) domains
alpha chains are composed of only V and J domains
what does “SP” refer to in CD4 SP
single positive
what type of HLA molecule produces an iNK T cell?
CD1d (glycolipid associated)
what are the subunits of the CD3 complex?
two epsilon, one gamma, one delta, two zeta
what is the entirely different subset of T cells called (apart from the alpha/beta T cells?)
gamma/delta - not otherwise tested
what three types of cells can be found in the thymus? (two others in trace amounts) what type of cell is conspicuously absent?
epithelial cells, mesenchymal cells, bone-marrow derived hematopoetic cells that develop into thymocytes; macrophages and dendritic cells in “small amounts”; B cells are conspicuously absent
in an SEM of the thymus, what types of cells are the tennis balls and what type make up the spindles?
T cells are balls, epithelial cells are the spindle
what determines the developmental fate of a T cell?
the signals that it receives from a peptide/HLA complex
what are the four alpha/beta T cell lineages? what HLA leads to these lineages? (what are the classes of the ligands bound to these HLA?)
CD4, CD4 Treg, iNK, CD8
HLA II, HLA II, CD1d, HLA I
(peptide, peptide, glycolipid, peptide)
the majority of cells in the thymus express what receptor?
double positive, meaning that they express both CD4 and CD8 receptors and have not been exposed to HLA I or II
where will you find no double positive cells?
in the lymph nodes
what types of cells show up as double negative cells in a scatterplot of CD4+ vs. CD8+ cells in the lymph nodes?
B cells
what is the first step in the formation of a T cell?
arrival of a stem cell in the thymus and the creation of a DN (double negative) cell
what cytokine acts as a growth factor that enables DN cells to mature into DP cells?
IL-7
what critical event happens in between the DN2 and DN3 substages? if this fails, what happens to the T cell?
beta gene rearrangement; in the event of failure, the T cell is developmentally arrested and eventually will die unless the problem is fixed
assuming successful formation of the TCR, what coreceptor molecules are expressed in the next stage of development? What is this stage of development called?
CD4 and CD8 coreceptors. Double positive stage (DP)
when do NK (note: NOT iNK) cells branch off on their developmental pathway?
prior to any VDJ rearrangements (prior to DN2-3)
what are the three developmental fates that can happen to a T cell (CD4 or CD8)
positive selection (weak handshake); negative selection (strong handshake); neglect (no handshake)
which of the three fates do most T cells undergo?
neglect
where do the peptide/HLA recognition sequences come from?
they are all “self” made, not foreign body
why does the system prefer the weak “handshake” to the strong one?
because too strong of a reaction to a “Self” peptide is likely to initiate an autoimmune reaction
what is the function of the AIRE protein?
to force thymic expression of tissue antigens that would not otherwise be in the thymus
what is used as a marker for the detection of T cell production?
TRECs
what is required for newly minted T cells to egress into the blood? what drug blocks this activity?
sphingosine 1 phosphate receptor (S1P1); FY720 (fingolimod)
