CH.4 B Flashcards
what gives rise to undifferentiated lymphocytes
red bone barrow
what cells do B and T cells come from
undifferentiated lymphocytes
what is the stroma made up of in the thymus
epithelial cells and connective tissue
where do T cells develop in the thymus
stroma
what % of lymphs in the peripheral blood are T cells
60 to 80
what is the T lymphocyte precursor
thymocytes
where do early thymocytes enter the thymus
corticomedullary junction
Once thymocytes enter the corticomedullary junction where do they go
outer cortex
what cytokine is critical for growth and differentiation of T cells
interleukin 7
what drives the T cell differentiation process
chemokine
how do thymocytes develop into t cells
rearrangement of genes
what is a double positive (DP) T cell
expresses CD 8+ and CD 4+
what is a double negative (DN) T cell
does not express either CD 8+ and CD 4+
T or F: the majority of intrathymic cells die before maturing
T
there is orderly _____ rearrangement of genes coding for the T cell receptor
random
what is specific about T cell maturation
distinct surface markers appear during diff stages
T or F: early thymocytes have CD4 and CD8 markers
F
what DNA chain on the TCR is rearranged 1st
beta
are the majority of T cells DP or DN
DP
what T cell receptor chains recognize Ag
alpha and beta
what part of the antigen do alpha and beta recognize on Ag
variable regions
how do TCR (T cell receptors) recognize different Ag
the alpha and beta chains get rearranged
what chromosome is the TCR beta chain
7
what region on the beta chain is rearranged 1st
C region
def? only one allele on 1 chromosome is rearranged
allelic exclusion
During pos selection what happens if T cells binds to self MHC
further differentiation
During pos selection what happens if T cells do not bind to self MHC
Apoptosis
During neg selection what happens if T cells binds to self Ag
apoptosis
what causes the activation of kinase enzymes
T cell receptor binding with MHC
where does positive selection of thymocytes occur
cortex
what happens if DP thymocyte interact too strong/weak with thymic epithelial cells
Apoptosis
T helper cells recognize what class of MHC
class II
what accounts of 2/3 of peripheral T cells
t helper cells
where does negative selection occur
medulla
T or F: survivors of T cell selection exhibit only one type of marker
T
what kind of T cells express CD 8+
cytotoxic T cells
T cytotoxic cells recognize what class of MHC
class I
what kind of T helper cell activate cytotoxic T lymphs and macrophages
Th1
what kind of T helper cell helps B cells produce Ab
Th2
what kind of t helper cell suppress immune resonse when needed
T regulatory cells
what do T regulatory cells secrete
inhibitory cytokines
what kind of t helper cell stimulate growth of mast cells and promote autoimmune inflammation
Th9
what kind of t helper cell increase inflammation and joint destruction
Th17
how long do T cells stay in the medulla
12 days
where do T cells get their 1st exposure to Ag
secondary lymphoid organs
how do T. cells make sure they get exposed to Ag
recirculate in blood stream every few hours
what happens once a T cell is exposed to an Ag
they become activated
what are the cell stages of B cell differentiation
Hematopoietic stem cell –> Pro B cell –> Pre- B cell –> immature B cell
what interacts with the C kit on the pro B Cell
stem cell factor
once C kit and stem cell factor interact what happens
DNA arrangement
what kind of B cell precursor has mu chains in the cytoplasm and alpha and beta chains on the surface
pre b cell
what kind of B cell precursor has IgM on surface
immature B cells
what is B cell central tolerance
B cells that bind to self ag –> apoptosis
If an immature B cell comes into contact with a blood borne pathogen what kind of B cell does it become
marginal zone B cell
if an immature B cell migrate to lymph nodes or there secondary lymph organ what kind of B cell do they become
follicular B cell
T or F: all types of B cells express IgM and IgD differently
F
what happens once a B cell comes into contact with a Ag
blast transformation
what is humoral immunity
plasma cell secreting Ab
T or F: T cells only respond to ag that are attached to MHC class I or II
T
what kind of cells have class I MHC
nucleated cells
what part of the Ab is always the same as the parent and clone
variable region
