Would someone please help me understand something about NK cells? Has
their lineage been defined yet? Our text book says that they act against
tumor cells and are involved in the non-specific early response to
infection with certain viruses and intracellular bacteria. I understand
that their activity is thought to be stimulated by IFN-alpha, IFN-beta, and
IL-2. What I don't understand is this: with most other immune cells (as
I understand it) there seems to be a relationship between lineage and
function. These cells seem to be the "guardians" that "hold down the fort"
until such a time as the necessary T(c) cells arrive on scene and begin
their differentiation into CTL's. It seems logical to me that these cells
could have differentiated from the Lymphoid stem cell. So here is my
question (I guess): Why does the fact NK cells develop in CB-17 SCID mice
suggest that they (NK cells) are not descended from the lymphoid stem cell?
(I thought that CB-17 SCID mice are fail to develop - MATURE - T and B
cells. Could it not be that the NK cells are still differentiated FROM
this pathway, but simply take a different path to maturation? I don't get
it. Forgive me if my question is 'naive.' I am sure that my ignorance of
some critical fact is what is causing my confusion. But I would greatly
appreciate any enlightenment a kind sole might be willing to impart.
Thank you in advance.
Therese at dfn.com