T lymphocytes Flashcards
What are the three family members of the lymphocytes?
T
B
Natural killer
What is meat by the term MHC restriction, in terms of T cells?
T cells are restricted in what they can respond to, since they require an MHC cell to activate them
What are the precursors to T cells called? Where are these produced, and where do they go to mature?
Prothymocytes, made in bone marrow, go to Thymus to mature
What are the two factors that differentiate T lymphocytes?
Functions and surface proteins
Where do T lymphocytes go once they mature in the Thymus/?
To lymphoid organs to await activation by antigen
Where are memory T cells found? What do they wait for?
Memory T cells tend to reside in the bloodstream until directed to enter non-lymphoid tissues to elicit cell-mediated immune responses.
What are the two subsets of T helper cells?
Th1 and Th2
What is the response generated by Th1? Th2?
Th1 = cell-mediated Th2 = humoral immunity
True or false: Th1 cells are exclusive in the fact that they only direct cell mediated immunity
False–there are actually cytokines that Th1 cells produce that stimulate B cells to produce IgG
What is the role Th17 plays?
Inflammatory response
What is the function of T-follicular helper cells?
promote germinal center formation in lymphoid organs
What is the function of cytotoxic T cells?
Lyse virus infected cells
Which lymphocytes are responsible for the form of DTH by reacting to noninfectious foreign antigens in the skin and causing a contact dermatitis (like poison ivy)
Cytotoxic T cells
What are T regulatory cells?
Cells that secrete cytokines to inhibit immune responses, thus acting to downregulate immunity once a pathogen has been eliminated
What are alpha-beta T Cell Antigen Receptor?
the proteins on the surface of T cells that allow them to recognize and respond to antigen
How many specific antigens can individual T cells recognize?
One
The TCR for most T lymphocytes is comprised of what parts? What binds these parts together?
an alpha and beta heterodimer, bound together by disulfide bridges
How are different specific TCRs generated?
Each chain on TCRs are composed of constant and variable regions similar to immunoglobulins
There are two chains (alpha and beta) on each TCR. Are both involved in binding to an antigen+MHC protein, or just one?
Both
True or false: The TCR is partly responsible for MHC restriction
False–not at all responsible. CD4 and CD3 are.
What produces MHC restriction?
CD4 and CD8 proteins
The cytoplasmic tails of the TCR chains are not long enough to act as signal transducers (t-rex!!). What transduces the signal from the TCR chains then?
CD3 proteins
What are the antigen receptor for B cells?
Antibodies
How many antigen bonding sites are on TCRs? B cell surface antibodies?
The TCR has a single antigen binding site, whereas the B cell antigen receptor has two antigen binding sites.
Are B cell antibodies secreted? How about the TCR protein on T cells?
B cell antibodies, yes
TCR, no
What are CD3 proteins? Are they variable between individuals? What subtypes exits? What sites exist in the tail that allows these proteins to act as signal transducers?
- Proteins that mediate the response of TCR proteins
- Invariable
- 1 gamma, 2 epsilon, and 2 zeta
- Phosphorylation sites in the tails