Development of T and B cells Flashcards
lymphoid system is the same as
immune system
by birth most hematopoiesis has moved to the____
bone marrow.
stem cells on average give rise to what two cells?
another stem cell and a daughter cell committed to differentiation.
What is the totipotent stem cell?
the fertilized ovum.
The HSC gives rise to what cells? What kind of potential does it have?
red and white cells and their derivatives including microglia of the brain. it is multipotential bc it cannot give rise to other kinds of cells.
What are the two differentiated daughters of the HSC? and what do they give rise to?
The common lymphocyte progenitor (CLP) and the common myeloid progenitor (CMP). CLP gives rise to B and T cell progenitors; CMP gives rise to everything else (progenitors of erythrocytes, megakaryocytes, eosinophils, mast cells/basophils, and the common granulocyte/monocyte progenitor from which neutrophils, macrophages, and most dendritic cells develop).
B cell progenitors are identified as such when?
When they begin to synthesize immunoglobulin components.
What is the order of immunoglobulin components synthesized and the names of the B cell as it matures?
Pro-B has mu detectable in the cytoplasm; it divides a couple times.
Pre-B cell has cytoplasmic IgM (cIgM) but no surface IgM or sIgM.
Immature B cell- begins to expose sIgM. Has extra membrane bound extension on the end of its Fc.
Mature B cell- Expresses both sIgM and sIgD and not longer has any cIgM.
how can you tell a mature B cell from an immature one?
Immature B cells have sIgM only. Mature ones have both sIgM and sIgD.
What is clonal deletion in a B cell and what is its purpose?
Clonal deletion occurs in order to prevent making antibodies against self. When immature B cells encounter antigen (they have IgM but no IgD) the cell tries receptor editing. If that fails then it dies. Thus, immature B cells that match with self will do so early on (in the bone marrow) and be forced to change their receptor or die so they don’t kill the body.
some anti-self B cells exist.
Helper T cells in the gut preferentially drive a M to _____ switch
A
In an immune response what do helper T cells do with B cells.
Help them switch to other forms of antibodies. IgM is secreted first in response to antigen. The helper T cells help switch from IgM to IgA, IgG, or IgE.
What does the switch helper mechanism prove?
That B cells in general do what helper T cells tell them to.
In secondary (booster) immunizations, which antibody will spike?
IgG. IgM is secreted for initial exposure and then helper T cells help make the transition to IgG for secondary responses. IgGs response aided by helper T cells is sooner, faster, higher, and more prolonged.
Fetus only makes IgM before birth. Where does it get IgG from?
IgG is from mother, the only immunoglobulin that can cross the placenta. It acquires the ability to make IgG 3-6 months postnatally. This makes sense because the half life for IgG is about 3 weeks. after 7 half lives very little mom IgG is left but baby has started making his own.
