Significance Of Natural Killer Cells Research Articles

Higher Dose of CD34+ cells Promotes Early Reconstitution of Natural Killer Cells and Is Associated with Better Outcomes After Unmanipulated Hematopoietic Stem Cell Transplantation for Myeloid Malignancies

Natural killer (NK) cells are the first lymphocyte population to recover after allogenic hematopoietic stem cell transplantation (allo-HSCT) and mediate potent graft versus leukemia effect, particularly in the settings of T-cell depletion. However, the significance of NK cells after unmanipulated transplantation is less clear, and factors affecting early NK reconstitution remain elusive. We retrospectively analyze 180 patients with acute myeloid leukemia or myelodysplastic syndrome who received unmanipulated allografts. We focus on the early NK reconstitution and its association with disease relapse, overall survival, and cytomegalovirus (CMV) reactivation. We also analyze factors that affect NK recovery, such as dose of CD34+ cells in the graft and T-cell recovery after transplantation. Penalized splines and receiver operator characteristic curves demonstrate a strong association between blood NK counts at 30 days after allo-HSCT (NK30) and all-cause mortality, with the cutoff value being close to the median value that divides patients dichotomously. Subsequent analysis shows that rapid NK recovery (higher NK30 or higher NK60) is associated with reduced disease relapse and better survival. Robust NK recovery (NK30 and NK60) also correlates with lower incidence of CMV reactivation. We find that NK30 is associated with the numbers of CD34+ cells (r = 0.739, P < .001) but not mature NK cells contained in the graft. In a small subset (N = 12) of the cohort, patients in continuous complete remission (N = 6) demonstrate higher frequencies of CD34+CD7+ progenitor cells and CD56bright NK cells in the day 30 bone marrow as compared to patients with disease relapse within 1 year (N = 6). Furthermore, neither T-cell recovery after transplantation nor application of anti-thymocyte globulins (ATG) in the conditioning regimen demonstrate suppressive effect on NK recovery. Rapid NK cell recovery is associated with improved prognosis of unmanipulated transplantation for myeloid malignancies. Manipulation of NK cell recovery represents a feasible approach to improve transplant outcomes for example by optimizing CD34+ cells in the graft.

Role of Natural Killer Cells during Pregnancy and Related Complications.

A high number of leucocytes reside in the human endometrium and are distributed differentially during the menstrual cycle and pregnancy. During early pregnancy, decidual natural killer (dNK) cells are the most common type of natural killer (NK) cells in the uterus. The increase in the number of uterine NK (uNK) cells during the mid-secretory phase of the menstrual cycle, followed by further increase of dNK cells in early pregnancy, has heightened interest in their involvement during pregnancy. Extensive research has revealed various roles of dNK cells during pregnancy including the formation of new blood vessels, migration of trophoblasts, and immunological tolerance. The present review article is focused on the significance of NK cells during pregnancy and their role in pregnancy-related diseases. The article will provide an in-depth review of cellular and molecular interactions during pregnancy and related disorders, with NK cells playing a pivotal role. Moreover, this study will help researchers to understand the physiology of normal pregnancy and related complications with respect to NK cells, so that future research work can be designed to alleviate the complications.

Presence and significance of NK cells in glioblastomas

A monoclonal antibody against the surface marker IOT-10 of natural killer (NK) cells was used to investigate the presence of these cells in a series of 25 glioblastomas. In 40% of the tumors, IOT-10-positive NK cells were found in small numbers scattered among the tumor cells. The presence of IOT-10-positive NK cells was not related to the degree of lymphocytic infiltration in the tumor as demonstrated by hematoxylin and eosin staining, nor did it appear to influence the survival time of the patients studied.

The distribution and possible significance of natural killer cells (HNK-1+ cell) in the human spleen.

The distribution of natural killer cells in human spleen was studied immunohistochemically and immuno-electron microscopically using a monoclonal antibody for human natural killer cell (HNK-1). The reactivity of this antibody to the formalin fixed and paraffin embedded specimens was confirmed and technical improvement was attempted. HNK-1+ cells were divided into two groups according to their distribution and cytological characteristics. One group consisted of cells distributed around the white pulp and in the red pulp and the other group localized in the germinal center (GC). The former morphologically resembled large granular lymphocyte (LGL) of peripheral blood and was thought to be the LGL of the blood circulating in the spleen. Although the latter consisted of lymphocytes having electron dense granules as LGL, their size and the ratio of nucleus to cytoplasm were greater than those of the former and their ultrastructural appearance indicated promoted secretory activity. The number of HNK-1+ cells in GC was intimately related to the development of GC. Furthermore, their population correlated with the number of mitoses of centroblasts, tingible body macrophages or peanut lectin-bound immature B lymphocytes, respectively. Based on these facts, a possibility was suggested that HNK-1+ cells in GC might be in an active phase and they might be related to the physiological regulation of differentiation and expansion of B cell. Phenotypic expression of HNK-1+ cells was examined by double immunoenzymatic labelling, but no differences were found between the HNK-1+ cells in GC and in the red pulp.