A to Z of N KCells:
A to Z of N KCells:-Women with larger populations of cytotoxic
CD16+ eNK cells(endometrial N K Cells) may be at greater risk for infertility
disorders and endometriosis . This is an effect of inflammatory influences of
endometriosis. CD16+ NK cells display cytotoxic activity towards trophoblasts
and endometrial cells.S
Angry
Routine assessment
of NK cells not recommended. But endometrial natural killer cells (eNK) are the most abundant
leukocyte population in the endometrium and have been thought to play a key
role in the etiopathogenesis of endometriosis and reproductive disorders. CD56 bright CD16- NK cells can produce angiogenic factors
that promote spiral artery remodeling and cytokines (LIF, leukaemia inhibitory
factor) that direct the migration of trophoblasts. Their function is controlled by
inhibitory receptors (NKG2a) and activating receptors (NKp46).
: Women with larger populations of cytotoxic CD16+ eNK cells may
be at greater risk for infertility disorders and endometriosis.
Further, the difference between infertility and recurrent loss
might represent a continuum of changes related to the inflammatory influences
of endometriosis. This is a study I am quoting.
One more interesting article....Pregnancy has been reported to
be associated with shift away from T-helper-1 (Th1)–type and bias toward
T-helper-2 (Th2)–type immune responses . The Th1/Th2 concept has been extended
by demonstrating that natural killer (NK) cells also can show comparable
polarities in their cytokine secretion profiles . The cytokine repertoire of
peripheral blood NK cells is mainly type 1 cytokines, such as interferon
(IFN)-γ and tumor necrosis factor (TNF)-α. However, NK cells can be induced
with stimulation to produce type 2 cytokines, such as interleukin (IL)-4, IL-5,
and IL-13 . There are additional types of NK cells, which produce transforming
growth factor-β (5) or IL-10 (NKr1) . It has been proposed that cytokine
production by NK cells facilitates decidualization, controls trophoblast
invasion, and promotes angiogenesis at the implantation site .
In peripheral blood, NK cells are either CD56bright or CD56dim cells, the main population being CD56dim NK cells. CD56bright cells are mainly present in the decidua although a relatively small population is present in the circulation. Recently, it has been reported that the type 2 shift during pregnancy is predominantly in the NK-cell (CD56bright and CD56dim) and NKT-cell (CD56+CD3+) populations instead of in the T-helper or cytotoxic T-cell populations .Type 2 shift is reported to be related to a significant decrease in type 1 cytokine production with no change in type 2 cytokine production by NK cells after in vitro stimulation in healthy pregnant women (10). Contrary to type 2 shift in normal pregnancy, the type 1 shift was present in women with pre-eclampsia predominantly in the NK cell populations.
Studies suggest that systemic regulation of peripheral blood NK cells is indicative of reproductive success, and implantation-related immune abnormalities, such as uterine NK cells, cytokines, and leukemia inhibitory factor, contribute to reproductive failure. The increase of cytotoxic NK cells in peripheral blood and endometrium was related negatively to the therapeutic results of IVF-ET . In women with recurrent SAB or repeated IVF-ET failure, peripheral blood NK cells have higher proportions of activated NK cells in vivo with unbalanced CD69 and CD94 expression .
A propensity to Th1 immune responses has been reported in women with recurrent SAB and implantation failures after IVF-ET systemically or locally. The presence of elevated Th1/Th2 cell ratios, high concentration of Th1 cytokines secreted by peripheral blood mononuclear cells (PBMCs), elevated NK cell cytotoxicity and levels, and emergence of various autoantibodies are the supporting evidence .Basically natural killer cells are important markers and have two sets of cells one is implantation friendly and another not so, but measuring their level in blood is not as beneficial as it would have been in endometrial tissue as these cells are very few in number and difficult for flow cytometry to catch it . Until unless some better tests are available we can't do it routinely.
In peripheral blood, NK cells are either CD56bright or CD56dim cells, the main population being CD56dim NK cells. CD56bright cells are mainly present in the decidua although a relatively small population is present in the circulation. Recently, it has been reported that the type 2 shift during pregnancy is predominantly in the NK-cell (CD56bright and CD56dim) and NKT-cell (CD56+CD3+) populations instead of in the T-helper or cytotoxic T-cell populations .Type 2 shift is reported to be related to a significant decrease in type 1 cytokine production with no change in type 2 cytokine production by NK cells after in vitro stimulation in healthy pregnant women (10). Contrary to type 2 shift in normal pregnancy, the type 1 shift was present in women with pre-eclampsia predominantly in the NK cell populations.
Studies suggest that systemic regulation of peripheral blood NK cells is indicative of reproductive success, and implantation-related immune abnormalities, such as uterine NK cells, cytokines, and leukemia inhibitory factor, contribute to reproductive failure. The increase of cytotoxic NK cells in peripheral blood and endometrium was related negatively to the therapeutic results of IVF-ET . In women with recurrent SAB or repeated IVF-ET failure, peripheral blood NK cells have higher proportions of activated NK cells in vivo with unbalanced CD69 and CD94 expression .
A propensity to Th1 immune responses has been reported in women with recurrent SAB and implantation failures after IVF-ET systemically or locally. The presence of elevated Th1/Th2 cell ratios, high concentration of Th1 cytokines secreted by peripheral blood mononuclear cells (PBMCs), elevated NK cell cytotoxicity and levels, and emergence of various autoantibodies are the supporting evidence .Basically natural killer cells are important markers and have two sets of cells one is implantation friendly and another not so, but measuring their level in blood is not as beneficial as it would have been in endometrial tissue as these cells are very few in number and difficult for flow cytometry to catch it . Until unless some better tests are available we can't do it routinely.
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