Up-regulation of NKG2A inhibitory receptor on circulating NK cells contributes to transfusion-induced immunodepression in patients with ß-thalassemia major.

Accumulating evidence has shown that allogeneic blood transfusions can induce significant immunosuppression in recipients, and thereby increase the risk of postoperative infection and/or tumor relapse. Although it is well known that natural killer (NK) cells are responsible for the immunodepression effects of transfusion, the underlying mechanisms remain obscure. In this study, we investigated the role of NK cells in transfusion-induced immunodepression in ß-thalassemia major. The proportion of circulating NK cells and the expression of NK receptors (NKG2A, CD158a, NKP30, NKP46 and NKG2D) as well as CD107a were detected by multicolor flow cytometry. IFN-γ production by circulating NK cells was detected by intracellular cytokine staining. Our results showed that the proportion and cytotoxicity (CD107a expression) of circulating NK cells in transfusion-dependent ß-thalassemia major patients were remarkably lower than those of ß-thalassemia minor patients or healthy volunteers. Expression of NKG2A inhibitory receptor on circulating NK cells in patients with ß-thalassemia major was remarkably up-regulated, but there were no significant differences in the expression levels of NKP30, NKP46, NKG2D, CD158a and IFN-γ. These results indicate NKG2A inhibitory receptor may play a key role in transfusion-induced immunodepression of NK cells in patients with ß-thalassemia major.

Association of maternal KIR and fetal HLA-C genes with the risk of preeclampsia in the Chinese Han population.

INTRODUCTION: This study is to investigate the distribution of inhibitory and activating killer-cell immunoglobulin-like receptors (KIRs) and the combination of KIR/human leukocyte antigen (HLA)-C in women with preeclampsia in the Chinese Han population. METHODS: A total of 271 patients and 295 controls were enrolled in our study. The inhibitory/activating KIR and HLA-C genes were detected using the PCR-SSP (polymerase chain reaction with sequence-specific primers) method. RESULTS: Our result showed that decreased numbers of individual activating KIR genes (2DS2, 2DS3, and 2DS5) were observed in women with preeclampsia. Furthermore, the gene frequency of total activating KIRs was significantly lower in patients compared with that of the controls (P = 0.03). The frequency of the KIR2DL1 gene was increased in women with preeclampsia when a homozygous HLA-C2 allele appeared in the fetus. CONCLUSION: The results suggest that a KIR genetic variation might influence the risk of preeclampsia. The lack of activating KIRs could possibly lower uterine natural killer (uNK) cell activation, thereby contributing to the pathogenesis of preeclampsia. Moreover, the imbalance of the inhibitory or activating signals at the maternal-fetal interface seems to play a regulatory role in the occurrence of preeclampsia.

Suppression of natural killer cell cytotoxicity in postpartum women: time course and potential mechanisms.

Little is known about the recovery of the immune system from normal pregnancy and whether the postpartum period is a uniquely adapted immune state. This report extends previous observations from our group of decreased natural killer (NK) cell cytotoxicity in the postpartum period. NK cytotoxicity was measured from 1 week through 9 months postpartum. In addition, NK cytotoxicity was assayed in the presence or absence of pooled plasmas collected from either postpartum or nonpostpartum women. Samples of cells were stained for inhibitory receptors and analyzed by flow cytometry. NK cytotoxicity remained decreased in postpartum women compared to controls through the first 6 postpartum months, returned to normal levels by 9 months, and remained normal at 12 months. NK cytotoxicity during the first 6 months was further inhibited by the addition of pooled plasma to NK cultures from postpartum women, but the addition of pooled plasma from the control group did not affect that group's NK cultures. There were differences in inhibitory receptor staining between the two groups, with decreased CD158a and CD158b and increased NKG2A expression on postpartum NK cells during the first 3 postpartum months. These data suggest that NK cytotoxicity postpartum inhibition lasts 6 months and is influenced by unidentified postpartum plasma components. The effect may also involve receptors on NK cells.

[Qualitative analysis of accented CD158a receptor expression in NK-lymphocytes in women with reproductive failures].

Blood from 91 women that undergoing IVF cycle was analysed for NK cells CD158a expression using a monoclonal antibody and FACScan flow cytometer and CellQuest software (BD Bioscience, San Jose, USA). Patients were separated on 3 groups according implantation and pregnancy results in actual IVF cycle. 53 patients not became pregnant (IVF failure group F), 24 became pregnant after IVF with subsequent successful pregnancy (Pregnancy succes group PS) and 13 became pregnant with subsequently pregnancy failure (Pregnancy failure group PF). Average levels of of CD158a on NK cells were significant increase in patients that not became pregnant compared to pregnant group. However IVF failure patients have comparable average CD158a levels to reproductive success group. Patients with pregnancy failure have significant decreased CD158a levels compared to both IVF failure and reproduct success patients. A qualitative analysis of NK CD158a expression showed that 22/24 (92.8%) women who became pregnant and live birth had CD158a levels that were > 20 but < 65%. In contrast only 62.8% patients form IVF failure and 61.6% from Pregnancy failure group had CD158a expression on NK in this zones (corridor). 38.4% of patients from pregnancy failure group had CD158a expression levels lower than 20% and as a result significant decreased average value in whole group. In contrast IVF failure patients had increased CD158a expression in 9.5% cases and decreased in 27.7% and as a result similar average levels to pregnancy success groups. Decreased CD158a expression (< 20%) was significant predictive factor for reproductive failure (OR 10,7) Increased CD158a expression > 65%) was predictive factor for Implantation failure (OR 5,4; P = 0,09) Normal CD158a expression (> 20% but < 65%) was significant predictive for IVF implantation and Pregnancy success and as a result for common Reproduct success (OR 2,7; 6,87; 6,92). We found that normal NK CD158a expression is associated with successful IVF and pregnancy. Preference of qualitative analysis under simple average value comparison in case of bilateral distribution of parameters was shown.

Biomarkers of suppressed natural killer (NK) cell function in metastatic melanoma: decreased NKG2D and increased CD158a receptors on CD3-CD16+ NK cells.

In metastatic melanoma (MM) patients we evaluated natural killer (NK)-cell activity, distribution of several NK receptors and their correlation with NK function. Peripheral blood lymphocytes (PBL) of MM patients and controls were analysed for NK activity and expression of activating NKG2D, CD161 and KIR, CD158a and CD158b receptors on CD3-CD16+ NK cells. MM patients not only had significantly decreased NK activity and NK-cell interferon (IFN)-gamma production, a redistribution of NK-cell subsets with an increase in CD16(dim) and a reduction in CD16(bright) NK subsets. There was a decreased CD161 and NKG2D and an increased CD158a NK-cell expression in MM patients, with a positive correlation between NKG2D expression and NK cytotoxicity and an inverse correlation between CD158b expression and NK-cell cytotoxicity in patients. Furthermore, patients' CD3-CD16(bright) NK subset showed lower expression of CD161 and CD158a. Therefore, NKG2D, CD158a and CD158b expression in MM patients may represent several clinically useful 'biomarkers' of suppressed NK function.

Elevated natural killer cell activity despite altered functional and phenotypic profile in Ugandans with HIV-1 clade A or clade D infection.

BACKGROUND AND OBJECTIVE: Natural killer (NK) cells most likely contribute toward limiting HIV-1 replication, and investigation into their function throughout the course of infection is therefore important. We here aimed to determine the state of the NK cell compartment in Ugandans with untreated HIV-1 clade A or D infection in comparison with matched uninfected controls. METHODS AND RESULTS: The function and phenotype of NK cells were investigated using 10-color flow cytometry. Surprisingly, NK cells displayed elevated production of interferon-gamma and macrophage inflammatory protein 1beta, as well as CD107a degranulation in infected subjects. This included unexpected levels of degranulation in the CD56bright subset of NK cells and high levels of macrophage inflammatory protein 1beta in CD56negative NK cells. HIV-1 infection was associated with reduced expression of KIR2DL1, NKG2A, CD161, and NKp30 in CD56dim and CD56negative NK cells, whereas lowered CD161 expression was the only alteration in the CD56bright subset. Interestingly, low CD4 counts were associated with increased levels of interferon-gamma and degranulation in CD56bright NK cells, as well as increased NKp44 expression in the CD56dim cells. CONCLUSIONS: NK cells in HIV-1-infected Ugandans display elevated activity, despite an altered functional and phenotypic profile. Furthermore, specific alterations in the CD56bright and CD56dim subsets occur in patients with severe CD4 loss.