Can natural killer cell activity help screen patients requiring a biopsy for the diagnosis of prostate cancer?

ABSTRACT Purpose To evaluate the usefulness of natural killer cell activity (NKA) in diagnosing prostate cancer (PC). Materials and Methods The medical records of patients who underwent transrectal prostate biopsy (TRBx) at Korea University Ansan Hospital between May 2017 and December 2017 were retrospectively reviewed. NKA levels were measured using NK Vue® Tubes (ATgen, Sungnam, Korea). All blood samples were obtained at 8 AM on the day of biopsy. Patients with other malignancies, chronic inflammatory conditions, high prostate-specific antigen (PSA) level (>20ng/mL), or history of taking 5-alpha-reductase inhibitor or testosterone replacement therapy were excluded. Results A total of 102 patients who underwent TRBx for PC diagnosis were enrolled. Among them, 50 were diagnosed with PC. Significant differences in age and NKA level were observed between the PC and no-PC groups. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off of NKA level for the prediction of PC was 500pg/dL, with a sensitivity of 68.0% and a specificity of 73.1%. In addition, NKA level (0.630) had the greatest area under the ROC curve compared to those for the ratio of total PSA to free PSA (0.597) and PSA density (0.578). Conclusions The results of this pilot study revealed that low NKA and high PSA levels were likely to be associated with a positive TRBx outcome. NKA detection was easy and improved the diagnostic accuracy of PC.

Evaluation of immunological parameters in pregnant women: low levels of B and NK cells / Avaliação dos parâmetros imunológicos em mulheres gestantes: baixos níveis de células B e NK

Abstract Objective To describe the immunological and hematological reference intervals of low-risk pregnant women. Methods A cross-sectional retrospective database analysis of a basic and translational study analyzing the hematological evaluation blood counts and immunophenotyping of TCD3 + , TCD4 + , TCD8 + , B, and natural killer (NK) cells of the peripheral blood in 79 low-risk pregnant women and of 30 control women from the state of Pernambuco, Brazil, was performed. Results No significant differences were detected between the hematological profiles of the 2nd and 3rd trimesters. Nevertheless, the median level of B cells decreased significantly in the 2nd (174 x 103 μL; p < 0.002) and 3rd trimesters (160 x 103 μL; p < 0.001), compared with the control group (296 x 103 μL). Similarly, the median level of NK cells was lower in the 2nd (134 x 103 μL; p < 0.0004) and 3rd trimesters (100 x 103 μL, p < 0.0004), compared with the control group (183 x 103 μL). In contrast, relative TCD4+ and TCD8+ levels increased in the 2nd and 3rd trimesters compared with the controls (TCD4 + : 2nd trimester = 59%; p < 0.001; 3rd trimester = 57%; p < 0.01; control = 50%; and TCD8 + : 2nd trimester = 31%; p < 0.001; 3rd trimester = 36%; p < 0.01; control = 24%). Conclusion Low-risk pregnant women have ~ 40% less B and NK cells in the peripheral blood, compared with non-pregnant women. These parameters may improve health assistance for mothers and contribute to define reference values for normal pregnancies.

Resumo Objetivo Descrever o intervalo de referência imunológico e hematológico de gestantes de baixo risco. Métodos Realizou-se uma análise retrospectiva, de um estudo básico e translacional, analisando o perfil hematológico e a imunofenotipagem das células TCD3 + , TCD4 + , TCD8 + , B e natural killer (NK) do sangue periférico de 79 gestantes de baixo risco e de 30 mulheres (controles) do estado de Pernambuco, Brasil. Resultados Não observamos diferenças significativas entre os perfis hematológicos do 2° e 3° trimestres. No entanto, houve redução das células B no 2° (média = 174 x 103 μL; p < 0,002) e no 3° trimestres (160 x 103 μL; p < 0,001), comparado como grupo controle (296 x 103 μL). A mediana das células NK foi menor no 2° (134 x 103 μL; p < 0,0004) e no 3° trimestres (100 x 103 μL; p < 0,0004), comparado com o grupo controle (183 x 103 μL). Porém, o percentual de TCD4+ e de TCD8+ aumentou no 2° e 3° trimestres em relação aos controles (TCD4 + : 2° trimestre = 59%; p < 0,001; 3° trimestre = 57%; p < 0,01; controle = 50%; e TCD8 + : 2° trimestre = 31%; p < 0,001; 3° trimestre = 36%; p < 0,01; controle = 24%). Conclusão Mulheres grávidas de baixo risco têm ~ 40% menos células B e NK no sangue periférico em comparação com mulheres não grávidas. Estes parâmetros podem melhorar a assistência à saúde das mães e contribuir para a definição de valores de referência para gestações normais.

Expression of dNK cells and their cytokines in twin pregnancies with preeclampsia

OBJECTIVES: To assess the expression of decidual natural killer (dNK) cells and their cytokines in twin pregnancies with preeclampsia. METHODS: This was a prospective case-control study. The inclusion criteria were diamniotic (monochorionic or dichorionic) twin pregnancies in the third trimester with negative serological results for infectious diseases; absence of major fetal abnormalities or twin-twin transfusion syndrome; and no history of administration of corticosteroids in this pregnancy. The control group (CG) included uncomplicated twin pregnancies, and the preeclampsia group (PEG) included twin gestations with clinical and laboratory confirmation of the disease according to well-established criteria. Samples of the decidua were obtained and analyzed by immunohistochemistry for the expression of dNK cells and interleukins (ILs) 10, 12 and 15. In addition, maternal serum samples were collected to determine the levels of these interleukins. RESULTS: Thirty twin pregnancies were selected: 20 in the control group (CG) and 10 in the preeclampsia group (PEG). The PEG showed strong placental immunostaining for IL-15 (p=0.001) and high maternal serum levels of IL-10 (22.7 vs. 11.9 pg/mL, p=0.024) and IL-15 (15.9 vs. 7.4 pg/mL, p=0.024). CONCLUSION: A higher maternal serum concentration of both pro- and anti-inflammatory factors was observed in the twin pregnancies in the PEG. However, no difference in placental expression of IL-10 was found between the groups. These findings may suggest that maternal attempts to balance these interleukins were not sufficient to cause a placental response, and this failure may contribute to the development of preeclampsia.

Comportamiento de las células asesinas naturales, las dendríticas y los macrófagos, en el embarazo / Behavior of the natural killer cells, dendritic cells and macrophages in pregnancy

La implantación de un embrión semialogénico en el útero materno constituye una paradoja inmunológica y es uno de los fenómenos que abre más interrogantes dentro del campo de la Inmunología. Mientras que en un determinado momento se consideró que la interfase materno-fetal era un sitio inmunológicamente privilegiado, hoy se sabe que ocurre un reconocimiento del feto semialogénico por el sistema inmune de la madre. Sin embargo, a pesar de este reconocimiento inmunológico se han descubierto varios mecanismos que pueden explicar el porqué la madre no rechaza al feto antigénicamente diferente. Estos mecanismos incluyen, tanto factores fetales como factores locales maternos, donde están incluidos los elementos de la respuesta inmunitaria adaptativa e innata. En este trabajo se hace referencia a la importante función que desempeñan las células asesinas naturales, las células dendríticas y los macrófagos en el embarazo(AU)

The implantation of a semiallogenic embryo in the womb is an immunological paradox and is one of the phenomena that open more questions in the field of immunology. While at one point it was considered that the maternal-fetal interface was an immunologically privileged site, now it is known that a fetus semiallogenic recognition by the immune system of the mother occurs. However, despite this immune recognition several mechanisms have been discovered that may explain why the mother does not reject the fetus antigenically different. These mechanisms include both fetal factors and local maternal factors, where the elements of innate and adaptive immune response are included. In this paper we refer to the important role of natural killer cells, dendritic cells and macrophages in pregnancy(AU)

Rapid flow cytometry based cytotoxicity assay for evaluation of NK cell function.

Assessment of natural killer cells (NK-cell) cytotoxicity is used not only in research settings but is also important in diagnosis of various diseases. NK-cell cytotoxicity assays are based on measurement of target cells killed by cytotoxic cells analyzed either by chromium (51Cr) release assay or flow cytometry. Both these methods use peripheral blood mononuclear cells (PBMC) or pure NK-cell population and hence require large volume of blood sample which is difficult to obtain in pediatric patients and patients with cytopenia. Hence, a flow cytometric assay was designed to determine NK cell activity using whole blood, eliminating the need for isolation of PBMCs or pure NK cells. This assay is based on a dual fluorescent staining of target cells (K562 cell line). The DIOC18 dye labeled K562 cells are incubated with whole blood and then counterstained with 7-AAD enabling the measurement of dead target cell and then percent cytotoxicity is calculated. This study compared the NK cell cytotoxicity using PBMC and whole blood in clinically relevant samples. There was no significant difference between two assays in the measurement of lytic activity or in reproducibility in the repeated samplings of healthy individuals. The whole blood assay required less volume of blood and also less processing time as compared to PBMC assay. It was also validated by testing patients diagnosed with familial hemophagocytic lymphohistiocytosis expected to have low NK-cell activity. This assay is rapid, sensitive and reproducible and requires significantly less volume of blood which is important for clinical evaluation of NK-cell function.

Variaciones en el número y función de los linfocitos asesinos naturales durante infecciones recurrentes o graves / Variation in NK cell number and function in individuals with recurrent or severe infections

Introducción. Existen pocos datos sobre los defectos que afectan el desarrollo y función de los linfocitos asesinos naturales ( natural killers, NK) en pacientes con un incremento anormal en la recurrencia de infecciones. Objetivo. Realizar una evaluación sistemática de las diferentes subpoblaciones y la función de estas células en pacientes con infecciones recurrentes. Materiales y métodos. Se incluyeron 20 pacientes con infecciones graves o recurrentes y se analizaron las subpoblaciones y la respuesta citotóxica de los linfocitos NK en sangre periférica. Los resultados de los pacientes se compararon con controles sanos pareados por edad y sexo. Resultados. Los pacientes con episodios infecciosos activos presentaron anormalidades transitorias en el porcentaje o el número absoluto de linfocitos NK. Se caracterizaron, además, cinco pacientes con alteraciones persistentes en la distribución de las subpoblaciones de linfocitos NK. Estas alteraciones se debieron principalmente a la disminución de células CD56 dim CD16 bright . Se evidenciaron, también, defectos en la función de los linfocitos NK en algunos de nuestros pacientes; sin embargo, estas alteraciones fueron transitorias y se asociaron principalmente a la fase activa de la enfermedad. Conclusiones. Nuestros resultados evidencian defectos transitorios en el número y función de los linfocitos NK en pacientes con infecciones recurrentes o graves, además de alteraciones persistentes en los LNK CD56 dim CD16 bright en algunos individuos. Es necesario profundizar en los mecanismos que conllevan al desarrollo de estos defectos inmunes y estudiar cómo estas alteraciones influyen en la respuesta inmune.

Introduction: The information about defects affecting natural killer cell (NK) development and activity in patients with an abnormal increase of recurrent infections is scarce. Objective: To perform a systematic analysis of NK abnormalities in patients with recurrent infections. Materials and methods: Our study enrolled twenty patients with severe or recurrent viral infections. Natural killer cell subsets, surface receptors expression and cytotoxicity were analyzed. Results were compared with those from age- and sex-matched healthy controls. Results: Transient alterations were observed in the percentages and absolute numbers of NK cells in patients with infection active episodes. We also described five patients with stable disturbances in the distribution of NK cell subpopulations. These defects are mainly due to a decrease in the CD56 dim CD16 bright cells in peripheral blood. In addition, NK cell function abnormalities were observed in some patients, however, those were always transient and mainly associated to active disease. Conclusions: These findings demonstrate transient alterations in the percentages and absolute numbers of NK cells in patients with recurrent or severe infection. Also, stable disturbances in CD56 dim CD16 bright NK cells are observed in these patients. Nevertheless, these parameters must be thoroughly studied to determine the mechanisms that entail these immune abnormalities and investigate how they alter the immune response.

The Correlation between NK Cell and Liver Function in Patients with Primary Hepatocellular Carcinoma

BACKGROUND/AIMS: This study aimed to detect the expression of natural killer (NK) cell receptor natural killer group 2D (NKG2D) in the peripheral blood of patients with primary hepatocellular carcinoma and to discuss the correlation between NK cell cytotoxicity and liver function. METHODS: The number of NK cells and the expression of NK cell receptor NKG2D in peripheral blood were determined by flow cytometry in patients with primary hepatocellular carcinoma, hepatitis B cirrhosis, chronic hepatitis B, and healthy controls. RESULTS: When compared with patients in the healthy and the chronic hepatitis B groups, the primary hepatocellular carcinoma group showed significant decreases in all parameters, including the cytotoxicity of NK cells on K562 cells, expression rate of NKG2D in NK cells, number of NKG2D+ NK cells, expression level of NKG2D, and number of NK cells (p<0.05). The activity of NK cells showed a positive correlation, whereas the Child-Pugh scores in the primary hepatocellular carcinoma and the hepatitis B cirrhosis groups showed a negative correlation with all parameters detected above. CONCLUSIONS: The decrease of NK cell activity in patients with primary hepatocellular carcinoma is closely related to their lower expression of NKG2D. Liver function affects the expression of NKG2D and the activity of NK cells.

O exercício físico e as células natural killer: uma revisão sistemática da literatura / Physical exercise and the natural killer cells: a systematic review

A célula natural killer, linfócito atuante no sistema inato, tem como funçãodestruir células tumorais ou infectadas por vírus. Essas células podem sofrer alterações com o exercício físico,qualitativa e quantitativamente, fato este que não é bem estabelecido na literatura. A presente revisão tem porobjetivo descrever a influência do exercício físico na contagem e função das células natural killer (NK Foi realizadauma busca em bases de dados internacionais, na qual 916 estudos originais com seres humanos relacionadosao exercício físico e às células NK foram encontrados, porém apenas 21 estudos atenderam a proposta doestudo. Observar-se na literatura que não há um consenso sobre a influência do exercício sobre a contageme a função das células NK. Essas diferenças nas respostas podem ser explicadas pelos diferentes protocolos deexercícios físicos, bem como pelos diferentes métodos de contagem dessas células. A intensidade e a duraçãodo exercício físico, em uma ampla margem, podem influenciar quantitativa e qualitativamente as células naturalkiller. Contudo, as características do estímulo físico ofertado permeiam as respostas das células natural killer.

The natural killer cell, lymphocyte active in the innate system, serves todestroy tumor cells or virus-infected. These cells are subject to change with physical exercise, qualitatively andquantitatively, this fact is not well established in the literature. The aim of this review is to describe the influenceof physical exercise in the count and function of natural killer cells. We performed a search in internationaldatabases, in which 916 original studies in humans related physical exercise and natural killer cells were found,but only 21 studies met the study proposal. It can be seen in the literature that there is no consensus on theinfluence of exercise on the count and function of natural killer cells. These differences in the responses canbe explained by the different protocols of physical exercise. The intensity and duration of exercise, may affectquantitative and qualitative natural killer cells. However, the features of the physical stimulus offered permeatethe responses of natural killer cells.

Doenças reumatológicas autoimunes e sua associação com os genes killer immunoglobulin-like receptors / Autoimmune rheumatic diseases and their association with killer immunoglobulin-like receptor genes

Os genes Killer Immunoglobulin-like Receptors (KIR) expressam-se como receptores que estimulam ou inibem as células Natural Killer (NK). As células NK fazem parte da imunidade inata e através de seus receptores KIR identificam células-alvo que apresentam moléculas HLA (Human Leukocyte Antigen) modificadas ou diferentes, induzindo à sua lise. Os receptores KIR são resultados da expressão dos genes KIR (19q13.14) na membrana celular das células NK, os quais são polimórficos e formam haplótipos. A diversidade de frequência dos haplótipos KIR em certas populações sugere que alguns indivíduos apresentam diferentes níveis de proteção contra algumas doenças e o balanço entre inibição e ativação celular mediada pelos receptores KIR e seus ligantes faz com que a célula NK possa auxiliar o organismo na vigilância imunológica. Além disso, há várias evidências da existência de associação de genótipos KIR ativadores com risco aumentado de doença autoimune.

Killer Immunoglobulin-like Receptor (KIR) genes express as receptors that activate or inhibit Natural Killer (NK) cells. The NK cells are part of the innate immune response and, through their KIR receptors, they identify target cells that have modified or different HLA (Human Leukocyte Antigen) molecules, inducing their lysis. The KIR receptors result from the expression of KIR genes (19q13.14) on the cell membrane of NK cells, which are polymorphic, and form haplotypes. The diversity of the frequency of KIR haplotypes in certain populations suggests that some individuals have different levels of protection against some diseases. The balance between cell inhibition and activation enables the NK cell to help the organism in immunological surveillance. In addition, there is evidence of the association of activating KIR genotypes with an increased risk for autoimmune disease.

Dynamics and kinetics of natural killer cell cytotoxicity in human malaria as evaluated by a novel stepwise cytotoxicity assay

Malaria causes important functional alterations of the immune system, but several of them are poorly defined. To evaluate thoroughly the natural killer cell cytotoxicity in patients with malaria, we developed a technique capable to assess both the dynamics and the kinetics of the process. For the kinetics assay, human peripheral blood mononuclear cells were previously incubated with K562 cells and kept in agarose medium, while for the dynamics assay both cells were maintained in suspension. NK activity from patients with vivax malaria presented a kinetics profile faster than those with falciparum malaria. NK cytotoxicity positively correlated with parasitemia in falciparum malaria. The dynamics of NK cytotoxicity of healthy individuals was elevated at the beginning of the process and then significantly decreased. In contrast, malaria patients presented successive peaks of NK activity. Our results confirmed the occurrence of alteration in NK cell function during malaria, and added new data about the NK cytotoxicity process.

A malária causa importantes alterações do sistema imunitário, muitas ainda mal definidas. Para permitir uma avaliação abrangente da atividade citotóxica das células natural killer em pacientes com malária, desenvolvemos um teste capaz de avaliar concomitantemente a dinâmica e a cinética do processo. Para a avaliação da cinética, células mononucleares do sangue periférico interagiram com células K562 e foram mantidas em agarose, enquanto para avaliar a dinâmica as células eram mantidas em suspensão. A cinética da atividade citotóxica das células NK foi mais rápida em pacientes com Plasmodium vivax, do que naqueles infectados com P. falciparum. Nestes, houve correlação positiva entre a atividade citotóxica das células NK e a parasitemia. O padrão da dinâmica da atividade citotóxica nos pacientes com malária foi bem diferente daquele apresentado pelos indivíduos sadios. Enquanto nestes, a atividade estava muito aumentada no início da incubação das células, sofrendo posteriormente uma redução, nos indivíduos infectados foram detectados sucessivos picos de atividade citotóxica. Nossos resultados confirmam a ocorrência de alteração funcional das células NK na malária humana e acrescentam novos dados sobre a dinâmica e a cinética da atividade citotóxica.

Natural killer cells in HIV-1 infection: role of NK cell-mediated non-cytolytic mechanisms in pathogenesis of HIV-1 infection.

Natural killer (NK) cells exhibit both cytolytic and non-cytolytic effector functions against HIV-infected targets. Their precise role in immunopathogenesis of HIV-1 infection is yet to be fully understood. This review addresses the non-cytolytic functions exhibited by NK cells, their potential role in pathogenesis of HIV-1 infection and the effect of HIV-1 viremia on NK cell functions. Activated NK cells are capable of secreting CC-chemokines and suppressing HIV-1 replication in a non-cytolytic fashion. However, HIV-1 viremia suppresses the ability of NK cells to secrete CC-chemokines. Suppression of HIV-1 viremia by highly active antiretroviral therapy (HAART) restores the ability of NK cells to secrete CC-chemokines and suppress endogenous HIV-1 replication by non-cytolytic mechanisms. Better understanding of the mechanisms involved in HIV-1-NK cell interactions would be helpful in delineating novel therapeutic strategics against HIV-1.

Activity of natural killer cells during HIV-1 infection in Brazilian patients

Natural killer cells are increasingly being considered an important component of innate resistance to viruses, but their role in HIV infection is controversial. Some investigators have found that natural killer cells do not confer a protective effect during the progression of HIV disease, whereas others have shown that natural killer cells may be protective and retard the progression of the disease, either through their lytic activity or by a chemokine-related suppression of HIV replication. In this study, we analyzed functional alterations in the activity of natural killer cells during HIV-1 infection using a natural killer cells activity assay with K562 cells as targets. RESULTS: Our results show that the activity of natural killer cells decreases only in the advanced phase of HIV infection and when high (40:1) effector cell-target cell ratios were used. The depression at this stage of the disease may be related to increased levels of some viral factors, such as gp120 or gag, that interfere with the binding capacity of natural killer cells, or to the decreased production of natural killer cells -activity-stimulating cytokines, such as IFN-a and IL-12, by monocytes, a subset of cells that are also affected in the late stage of HIV infection. The data suggest that decreased natural killer cells cell activity may contribute to the severe impairment of the immune system of patients in the late stages of HIV infection

Células natural killer y el sistema inmune innato en la patología infecciosa / Natural killer cells and the innate immune system in infectious diseases

Natural killer (NK) cells form a unique third group of lymphocytes that differs from T and B cells in surface phenotype, target cell recognition and function. NK cells have two relevant functions, related to the innate immune response against pathogens microorganisms. One is cytotoxicity, mediated by the recognition and lysis of target cells such as virus and bacteria infected-cells. The second NK cell function is to produce cytokines, mainly IFN-g, that can modulate innate and specific immune responses. Cytotoxicity and cytokine secretion contribute to host resistance against microorganisms and both functions are significantly altered in infectious diseases

Restoration of P-glycoprotein function is involved in the increase of natural killer activity with exogenous interleukin-15 in human immunodeficiency virus-infected individuals

A depressed level of natural killer (NK) activity is one of the various immunologic abnormalities in human immunodeficiency virus (HIV) infection. Interleukin-15 (IL-15), an immunotherapeutic candidate in HIV infection, increases NK activity and induces the excretion of CC-chemokines from divergent immune cells, but the mechanisms of NK activity enhancement by IL-15 stimulation is not clearly established in HIV infection. This study examined whether CC-chemokines, which are known to increase NK activity, are secreted adequately in HIV-infected individuals, and also investigated whether P-glycoprotein is involved in NK activity enhancement after IL-15 administration. NK activity increased with IL-15 stimulation in NK cells of HIV-infected individuals, as it does in normal NK cells. IL-15 stimulates NK cells to secrete CC-chemokines, such as, macrophage inflammatory protein-1alpha (MIP-1alpha), macrophage chemotactic protein-1alpha (MCP-1alpha) and regulated upon activation, normal T cells expressed and secreted (RANTES) in both HIV-infected individuals and controls with no significant difference. P-glycoprotein expression and function is decreased in HIV-infected individuals and restored only in NK cells of HIV-infected individuals after IL-15 stimulation. P-glycoprotein may play a role in the mechanism of increased NK cell activity in HIV-infected individuals after IL-15 stimulation.

Natural killer cells and interleukin-12 in patients with advanced cervical cancer under neoadvanced chemotherapy

Patients with advanced cervical cancer have deficient natural killer (NK) cell activity, usually as a consequence of tumor invasion, which results in tumor NK cell sequestration. The reason for the occurrence of such alterations in patients under chemotherapy is unknown. We evaluated the activity and number of NK cells and T cell subpopulations in ten patients before and three weeks after neoadjuvant chemotherapy (CT). The schedule used was cis-platinum (100 Mg/M2 per cycle) and bleomycin (15 mg/cycle), repeated every 28 days. Although there were similar levels of NK cells before and after CT in both groups, we observed greater cytotoxicity of peripheral blood lymphocytes and increased levels of CD4+ and CD8+ T cells (P<0.01) in five patients who presented a good clinical response when compared to the group with a poor response. IL- 12, known to increase NK cell activity when added to peripheral blood lymphocyte cultures, markedly increased lytic activity before and after CT only in the group with a good clinical response. These results suggest that NK cells from the poorly responding patient group express less lytic activity per NK cell and are insensitive to IL- 12 stimulation, probably as a result of reduced IL-12 receptor expression or a defective intracellular transduction mechanism. The present findings may be useful as a prognostic factor in clinical practice and also provide support for human clinical trials of IL- 12 and neoadjuvant CT for the treatment of malignant cervical tumors.

Studies of natural killer cells in pregnancy-induced hypertension

The number and activity of natural killer (NK) cells were studied in 20 patients with pregnancy-induced hypertension (PIH), 15 uncomplicated pregnant women and 16 healthy non-pregnant women. All the pregnant women were evaluated during the third trimester of gestation. Peripheral blood NK cells were detected with monoclonal antibodies by indirect immunofluorescence and cytotoxic activity was measured using a single-cell assau against K562 target cells, Hypertensive pregnant women had an increased number of circulating NK cells associated with a significant decrease of NK activity. The cytotoxic activity was significantly lower in normal pregnant and PIH women when compared with non-pregnant controls. The onset of immune NK cells in peripheral blood and the impairment of their cytotoxic activity in PIH patients may be associated with hormones and immunosuppresive substances produced by tissues occurring at the maternal-fetal interface