Natural killer (NK) cell receptors' repertoire in couples with recurrent spontaneous abortions

PROBLEM: Natural killer (NK) cell receptors (NKRs) have been suggested to protect trophoblast, but their function at the fetomaternal interface remains unknown. To investigate if the outcome of pregnancy depends on women's NKRs, we studied the NKR repertoire in couples with recurrent spontaneous abortions (RSA). METHODS: Twenty-six childless couples with > or = 2 abortions, characterized by alloimmune abnormalities, and 26 control couples were genotyped for five killer immunoglobulin-like receptors (KIR) and two CD94/NKG receptors, known to have as ligands human leukocyte antigen (HLA) class I molecules with trophoblastic expression: inhibitory 2DL1,2,3 and activating 2DS1,4 KIRs, inhibitory NKG2A and activating NKG2C. Detected repertoires of women and partners were compared between the two groups. RESULTS: Less aborters than controls were found to have all three inhibitory KIRs (30.77% versus 69.23%, P = 0.01), some of them had only one inhibitory KIR (19.23% versus 3.85%, P = 0.08) and most of them were lacking inhibitory KIRs possessed by their husbands (57.69% versus 15.38%, P = 0.001). CONCLUSIONS: Women with alloimmune abortions have a limited inhibiting KIR repertoire and such miscarriages may occur because trophoblastic HLA class I molecules are recognized by decidual NK cells lacking the appropriate inhibitory KIRs.     

ORIGINAL ARTICLE: How Valuable is Measurement of Peripheral Blood Natural Killer Cells at the Time of Abortion?

PROBLEM: Increased peripheral blood natural killer (NK) cells are associated to immune-mediated abortion, but their diagnostic value when measured at the time of miscarriage is unknown. METHOD OF STUDY: In women with therapeutic (A = 79) or elective (C = 34) pregnancy termination, the NK-cell percentage was measured before and 5 days after curettage. Additionally, immune-mediated lesions (scored 0-3) and CD56(+) and CD16(+) decidual NKs (scored 1-3) were detected on the abortion material. RESULTS: Aborters differed from controls in histological scores (P = 0.000) and in NK percentage (>12%) only in the measurement 5 days after the operation (P = 0.038). In comparison to histological lesions, NK measurement was found to have sensitivity 70%, specificity 73.68%, positive prognostic value 89.39% and negative prognostic value 43.75%. CONCLUSION: An Increased NK-cell percentage 5 days after the pregnancy termination could be a marker of immune aetiology of miscarriage, as the probability of an aborter with NK >12% to have an immune-mediated abortion is almost 90%.     

Simple enumerations of peripheral blood natural killer (CD56+ NK) cells, B cells and T cells have no predictive value in IVF treatment outcome

BACKGROUND: To evaluate the association between the absolute counts of the peripheral natural killer (NK) cells (including total CD56(+) NK cells, CD56(dim) NK cells and CD56(bright) NK cells), B cells and T cells on the implantation rate and miscarriage rate after IVF treatment. METHODS: This was a prospective observation study. A total of 138 patients who underwent IVF treatment from December 2002 to July 2003 were recruited to the study. Blood samples were obtained on the day of vaginal oocyte retrieval prior to the procedure. The absolute counts of lymphocytes, NK cells, B cells and T cells were identified by flow cytometry. These absolute counts and their relationships to IVF treatment outcome and miscarriage rate were analysed. RESULTS: There were no significant differences with regard the mean values of absolute lymphocyte count, T cell count, B cell count and NK cell count (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells) between the pregnant and non-pregnant groups and also between the ongoing pregnancy and miscarriage groups. The cause of infertility, duration of infertility, basal FSH levels, number of previous failed IVF treatments, number of previous miscarriages and stimulation characteristics were not significantly different between the pregnant and non-pregnant groups. Previous studies have suggested that women with a history of recurrent miscarriage and those with infertility accompanied by recurrent failed IVF treatments are associated with a peripheral blood NK cell percentage >12%, therefore further analysis of peripheral CD56(+) NK cell levels <12% (group A) and >12% (group B) was performed. There was no significant difference in implantation rate (group A: 17.0%; group B: 23.2%), pregnancy rate (group A: 36.6%; group B: 47.7%) or miscarriage rate (group A: 23.3%; group B: 28.6%). CONCLUSION: There were no significant differences between simple enumerations of peripheral blood NK cells (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells), B cells and T cells with IVF treatment outcome and pregnancy outcome. Women who had a peripheral NK cell level >12% did not have higher number of previous pregnancy losses. Importantly their pregnancy rate was not reduced and their miscarriages were not increased compared to women who had a peripheral NK cells level <12%.     

Psychosocial factors regulating natural-killer cell activity in recurrent spontaneous abortions

PROBLEM: The preconceptional natural-killer cell (NK) activity predicts subsequent miscarriage among women with unexplained recurrent spontaneous abortion (RSA). Psycho-neuro-immuno-endocrine network has recently been proposed as a mechanism for abortions. We therefore examined which psychosocial factors influenced the NK activity among women with RSA. METHOD OF STUDY: We measured the preconceptional NK activity of 61 women with a history two consecutive unexplained first-trimester miscarriages and no live births. We also administered semi-structured interviews and a battery of self-report questionnaires to assess their social support, personality, self-esteem and psychiatric symptoms. RESULTS: The preconceptional NK activity was negatively correlated with the women's neuroticism personality trait (r= -0.32, P = 0.01) and current depressive symptoms (r = -0.26, P= 0.05), and positively correlated with their self-esteem (r = 0.34, P = 0.01). CONCLUSIONS: In addition to several substances such as transforming-growth-factor beta and granulocyte-macrophase colony-stimulating factor, we found that low neuroticism, low depression scale score and high self-esteem contributed to high NK activity among women with RSA.     

Adverse influence of numbers of previous miscarriages on results of paternal lymphocyte immunization in patients with recurrent spontaneous abortions

PROBLEM: To determine whether an increase in the number of previous miscarriages in recurrent spontaneous abortion patients is a risk factor in subsequent pregnancies with paternal lymphocyte immunotherapy. METHOD OF STUDY: Live birth rates with reference to previous abortion numbers in recurrent spontaneous abortion patients were statistically compared between paternal lymphocyte immunotherapy and control groups, the latter retrospectively researched using historical data before 1981 in our clinic. RESULTS: The overall live birth rate was 73% (169/232) in the immunotherapy group, and 48% (47/97) in controls (P <0.05). According to previous abortion numbers, the rates were 77% (114/148) versus 55% (36/65) (P < 0.05) for three previous abortions, 70% (40/57) versus 38% (8/21) (P < 0.05) for four and 56% (15/27) versus 27% (3/11) (not significant) for five, in the study and control groups, respectively. CONCLUSIONS: The results confirm the efficacy of paternal lymphocyte immunotherapy, but demonstrate that the success rate deteriorates with the number of previous miscarriages.     

Divergence of natural killer cell receptor and related molecule in the decidua from sporadic miscarriage with normal chromosome karyotype

The aim of this cohort study was to investigate immunophenotypic characteristics of natural killer (NK) cells by assessing specific molecules expressed in the decidua of sporadic miscarriages and induced abortions. The deciduae were obtained from 29 consecutively seen women whose pregnancies ended in first trimester miscarriages (MS), and the fetal chromosome karyotype of these MS was analysed. Additionally, 13 deciduae were obtained from induced abortion (IA) with informed consent. The expression of perforin, CD94, CD161, CD158a, CD158b, CD244 on CD3-CD56+NK cells, and perforin on CD3+CD8+ T cells was analysed by flow cytometry. The CD158a (mean+/-SD, 26.2+/-14.7%) and CD94 (50.2+/-25.7%) expressions in MS with normal chromosome karyotype (MSNK; n=11) were significantly decreased as compared with those (41.5+/-19.5%, 71.4+/-20.4%) in MS with abnormal karyotype (MSAK; n=18) and those (44.3+/-21.9%, 80.8+/-17.5%) in IA (n=13). Conversely, the perforin expression on CD3-CD8-CD56+NK cells (76.3+/-11.0%) and CD3+CD8+T cells (30.6+/-9.2%) in MSNK was significantly increased as compared with those (66.8+/-16.6%, 23.6+/-8.7%) in MSAK and those (62.9+/-11.6%, 19.7+/-8.1%) in IA. A positive correlation between CD94 and CD158a expressions on NK cells, negative correlations between CD94 on NK cells and perforin on NK cells/T cells, and between CD158a on NK cells and perforin on T cells were found in the decidua. A divergence of NK cell repertoire in the decidua might be related to aetiology of sporadic MSNK.     

Up-Regulated Expression of CD56+, CD56+/ CD16+, and CD19+ Cells in Peripheral Blood Lymphocytes in Pregnant Women With Recurrent Pregnancy Losses

PROBLEM : To analyze immunophenotypic profiles of peripheral blood and humoral autoimmune responses in women with a history of recurrent spontaneous abortions (RSA). METHOD : Peripheral blood lymphocyte subsets by flow cytometry and autoantibodies to phospholipids and nuclear components by ELISA were measured in non pregnant and pregnant women with RSA of unknown etiology. Thirty-five pregnant and eighty-one nonpregnant women with RSA were studied. Seventeen nonpregnant and twenty-two pregnant normal controls were included. RESULTS : Natural killer (NK) cells (CD56+) were significantly elevated in nonpregnant women with RSA as compared with nonpregnant controls. Pregnant women with RSA demonstrated significantly increased NK (CD56+, CD56+/CD16+) and B cells (CD19+) as compared with pregnant controls. Women who miscarried the index pregnancy demonstrated significantly lower CD3+ cells in comparison with normal controls. Women with RSA and antiphospholipid antibodies showed significantly elevated NK cells when compared with women without antiphospholipid antibodies. Women with autoantibodies to nuclear components demonstrated significantly elevated CD19+/CD5+ cells when compared to women without autoantibodies to nuclear components. CONCLUSIONS : Women with RSA demonstrate an abnormal cellular immune response by increasing peripheral natural killer cells and B cells as compared with normal controls.     

Specialist contraceptive counselling and provision after termination of pregnancy improves uptake of long-acting methods but does not prevent repeat abortion: a randomized trial

BACKGROUND: One in four abortions in the UK is undertaken for women who have had one before. Women undergoing abortion in Edinburgh were targeted for improved contraceptive advice and provision in this randomized trial. METHODS: Between November 2001 and May 2002, women recruited at assessment for abortion were randomized at admission to receive specialist contraceptive advice and enhanced provision (316 women) or standard care (297 women). Randomization was based on the week of admission. Contraceptive use 16 weeks after abortion was assessed by questionnaire and subsequent abortions by review of the hospital records 2 years later. RESULTS: Women receiving specialist advice and enhanced provision were more likely to leave the hospital with contraception (271 versus 115, P < 0.001), which was more likely to be a long-acting method (141 versus 78, P < 0.001) than women receiving standard care. Four months later, there was no significant difference in contraceptive prevalence or continuation, but women in the intervention group were more likely to be using contraceptive implants (32 versus 6, P < 0.001). Two years later, 14.6% of women in the intervention group (44/302) and 10% of controls (27/268) had undergone another abortion in the same hospital (P = 0.267). CONCLUSIONS: Specialist contraceptive advice and enhanced provision had a short-lived effect on contraceptive uptake and increased the use of long-acting methods but did not appear to reduce repeat abortions.     

Preconception peripheral natural killer cell activity as a predictor of pregnancy outcome in patients with unexplained infertility

PROBLEM: Preconception high peripheral natural killer (NK) cell activity in women with recurrent spontaneous abortion can predict subsequent miscarriages. We have examined prospectively, for the first time, the pregnancy rate in patients with unexplained infertility by measuring the peripheral NK activity. METHOD OF STUDY: We tested the peripheral NK activity of 94 infertile women who despite treatment were unable to conceive for 6 or more months (mean; 2.4 years). Peripheral NK activity was measured by a chromium-51 release cytotoxicity assay. Women were followed for 2 years and assessed. RESULTS: In 77 patients who were followed for 2 years, 28 had conceived but 49 did not. The peripheral NK activity of the group that became pregnant (mean +/- S.D.; 34.5 +/- 13.8%) was significantly lower than that of non-conception group (42.3 +/- 13.3%, P = 0.017). CONCLUSIONS: Our finding suggests that elevated peripheral NK activity in patients with unexplained infertility is a risk factor for attaining pregnancy success.     

Placental C4d as a common feature of chromosomally normal and abnormal miscarriages

Placental C4d deposition is a feature of classical complement pathway activation and has been documented in various obstetrical settings. However, it is unknown whether placental C4d deposition is present in miscarriages and its frequency is different between chromosomally normal and abnormal miscarriages. This study was conducted to assess villous C4d deposition in miscarriages and to determine whether its frequency is different between chromosomally normal and abnormal miscarriages. Tissue samples (N?=?58) of elective abortions (n?=?20), miscarriages with normal chromosomes (n?=?15), trisomy 16 (n?=?13), and trisomy 22 (n?=?10) were analyzed. Immunohistochemical staining for C4d and CD138 was done. Placental C4d deposition was defined as linear C4d immunoreactivity along the syncytiotrophoblast. Placental C4d immunoreactivity was detected in 73.3 % (11/15) and 56.5 % (13/23) of miscarriages with normal chromosomes and trisomy cases, respectively, while it was found in 5 % (1/20) of elective abortions (p?<?0.05). Placental C4d deposition was more frequent in recurrent miscarriages (previous spontaneous abortion ≥2) than in sporadic miscarriages (76.5 vs. 30.0 %; p?=?0.001). Chronic deciduitis was observed in 20.0 % (3/15) and 30.4 % (7/23) of miscarriages with normal chromosomes and trisomy cases, respectively, but not in elective abortions (p?=?0.07 and 0.01, for each). The frequencies of C4d deposition (46.2 vs. 70.0 %) and chronic deciduitis (38.5 vs. 20.0 %) were not also different between trisomy 16 and trisomy 22 cases. Placental C4d deposition is a prominent feature of miscarriages regardless of their chromosomal status. The overall findings suggest that complement-mediated placental injury is a common pathology of miscarriage with diagnostic values in routine pathology practice.     

Further experience with intravenous immunoglobulin in women with recurrent miscarriage and a poor prognosis

PROBLEM: Women with three or more unexplained miscarriages have a 60% chance of a subsequent live birth. Intravenous immunoglobulin (IVIG) has not been conclusively shown to improve this prognosis. This study assessed the effect of IVIG in patients expected to have a poor outcome if untreated, i.e. women with five or more abortions, who have aborted after paternal leukocyte immunization or who continue to abort despite expressing anti-paternal complement dependent antibody. METHODS: Seventy-six women received IVIG in a dose of 400 mg/kg body weight, in one day (total 30-45 g) in the follicular phase of a cycle in which pregnancy was planned. A booster dose was administered when pregnancy was diagnosed. Their results were compared to an untreated control group of 74 women. RESULTS: Thirty-five (49%) pregnancies in treated women have resulted in live births or passed their previous stages of abortion compared to 23 (31%) in control patients (P = 0.04). CONCLUSIONS: These figures indicate that IVIG may prevent further miscarriages in this poor prognosis population. These figures are especially significant considering the doubt concerning the efficacy of IVIG in patients with three miscarriages and therefore a relatively good prognosis.     

LPS-induced murine abortions require C5 but not C3, and are prevented by upregulating expression of the CD200 tolerance signaling molecule

PROBLEM: Lipopolysaccharide (LPS) acts via tlr4 to promote Th1 cytokine secretion and abortions. LPS is an essential co-factor in spontaneous abortion in the CBA x DBA/2 model and in stress-triggered abortions. In the CBA x DBA/2 model, C3a, C5a, and fgl2 prothrombinase participate in triggering inflammation that terminates embryo viability. As fgl2 prothrombinase (via thrombin) can generate C5a, it was predicted that LPS-driven abortions (which require fgl2) would be independent of C3. CD200Fc can prevent abortions in the CBA x DBA/2 model, but an action through Fc could not be excluded. METHOD OF STUDY: C3(-/-) and C5(-/-) knock-out mice on a B6 background were syngeneically mated and Salmonella enteritidis LPS was administered i.p. on day 6.5 or pregnancy along with 2 mg progesterone in sesame oil s.c. The total number of implants and the number of resorbing embryos were counted on day 13.5 of pregnancy. CD200-rtTA double transgenic homozygous males (B6 background) mated with B6(+/+) females were similarly treated. To up-regulate CD200 expression in embryonic trophoblasts, doxycycline was added to the drinking water from the time of mating. RESULTS: The LPS boosted the abortion rate from 15.5% (control) to 42.0% in C3(-/-) mice (chi(2) = 9.28, P < 0.005). In C5(-/-) mice, there was no increase in abortion rate with LPS compared to progesterone-treated controls (22.8%versus 26.3%, P = NS). LPS-treated transgenic mice given LPS + progesterone had a 42.5% abortion rate, but when the mice were given doxycycline to induce expression of CD200 by the embryo, the abortion rate was only 8.3% (chi(2) = 14.40, P < 0.005, Fisher's exact test P = 0.00007). CONCLUSION: C5, but not C3, appears necessary for LPS-driven abortions. Up-regulation of CD200 can prevent LPS-driven abortions, possibly by altering dendritic cells to promote Treg cell development or by a direct suppressive action on macrophages and mast cells that also express CD200 receptors.     

Immunopathology of the implantation site utilizing monoclonal antibodies to natural killer cells in women with recurrent pregnancy losses

PROBLEM: Placental lesions of 71 women with documented recurrent spontaneous abortions of unknown etiology were evaluated using immunohistochemical staining. METHOD OF STUDY: Placental tissue blocks (less than 12 weeks gestation) from prior pregnancy losses were obtained, recut, and analyzed utilizing monoclonal antibody to identify the trophoblast (cytokeratin 8/18) and natural killer (NK) cells (CD57) at the implantation site. The following features were evaluated: trophoblast invasion pattern; syncytium formation; vasculitis and thromboembolism of decidual vessels; decidual inflammation; decidual necrosis; fibrin deposition at the decidual necrosis site; mononuclear-cell infiltration in villi and intervillous space; perivillous fibrin deposition; trophoblast morphology; and quantitation of CD57+ NK cells within the decidual tissue near the implantation site. Controls consisted of 20 healthy women with no history of recurrent pregnancy losses, who had their pregnancies electively terminated. RESULTS: Of the women studied, 29.6% demonstrated elevated CD57+ NK cells at the implantation site (P = 0.030), 54.1% had inadequate cytotrophoblast invasion depth (P = 0.000), 44.1% demonstrated inadequate syncytium formation (P = 0.004), and 33.9% presented thromboembolism in decidual vessels (P = 0.025). CONCLUSION: Some women with recurrent spontaneous abortions demonstrate abnormal placental lesions at the implantation site. Immunopathologic evaluation of the placental implantation site that terminated in a spontaneous abortion may reveal the immunopathogenesis of previous pregnancy losses.     

Spontaneous abortion and psychosomatics. A prospective study on the impact of psychological factors as a cause for recurrent spontaneous abortion

A group of 36 patients who had had at least two consecutive spontaneous abortions and who desired to have children was subjected to a psychosomatic investigation before a biomedical diagnostic screening programme was started. A semi-structured interview regarding sociodemographic data, current relationship, social support, education, occupation and medical anamnesis was carried out. In addition, all women completed four standardized questionnaires on the topics of anxiety, somatization disorder, life satisfaction and depression. A control group of 36 women, matched for age and occupation, was subjected to the same psychosomatic investigation. The findings of the diagnostic screening programme showed that 16 women had abortions because of physical abnormality, and 15 women had no physically confirmed cause (in five women, the investigations were not completed). Following recurrent spontaneous abortion, 18 women had a successful pregnancy within 2 years, and 18 women were still childless. The comparison between patients and the control group revealed that patients with recurrent abortion were significantly more satisfied with their life quality regarding leisure time, financial situation and occupation. No significant differences were observed in any other variables. Patients who suffered spontaneous abortions due to a physical disorder showed partner relationship of longer duration, and more frequent miscarriages. Women with successful pregnancy within 2 years after recurrent miscarriage were significantly younger and had fewer physically related abortions compared with women who remained childless. In summary, psychological factors seem to be of subordinate importance as a cause for recurrent spontaneous abortion. Moreover, physical abnormalities in the reproductive system have a predominant impact on the prediction of a future successful pregnancy.      

Predictors of pregnancy success in repeated miscarriage.

Factors that may have a bearing on subsequent pregnancy success or failure in patients with recurrent abortion were examined in 165 women with a history of three or more consecutive miscarriages in the first trimester. The overall success rate was 67.9%. Factors that were found to correlate significantly with success rate were length of abortion history, total number of abortions, interval from last miscarriage to present pregnancy, and whether there was any degree of subfertility. Logistic regression analysis showed that the abortion x years index and maternal age accounted for all the variation observed in our data. Where all other known causes of abortions are excluded, recurrent aborters can be subdivided into two populations--namely, those with a relatively good prognosis characterized by a short abortion history and absence of subfertility problems, compared to those with a poor prognosis namely those with a long abortion history or presence of subfertility problems. These data clearly demonstrate major differences in success rates in women depending on the number of abortions and the length of abortion history (abortion x year index), particularly in women over the age of 30 years.     

Serum levels of folate and cobalamin in women with recurrent spontaneous abortion

We evaluated the folate and cobalamin status in 29 non-pregnant women with a history of recurrent spontaneous abortion (three or more consecutive) of unknown aetiology in comparison to 29 healthy nulligravidae of similar reproductive age (controls). Serum concentrations of folate and cobalamin showed no significant differences between the two groups. No correlation between age and vitamin concentrations was found. In the study group there was a significant negative correlation of the number of previous abortions and the concentration of serum folate. Patients with at least four previous miscarriages had significantly lower serum values of folic acid than women with three abortions, but not than controls. The underlying cause of this finding remains unclear. In conclusion, the serum concentrations of folic acid and vitamin B12 are not significantly altered in women with unexplained recurrent spontaneous abortions, and an association between a deficiency of these vitamins and an increased risk of pregnancy loss appears to be questionable in the majority of gestations.      

Endocrine abnormalities during the follicular phase in women with recurrent spontaneous abortion.

The frequency of endocrine abnormalities during the follicular phase in non-pregnant women with a history of recurrent abortion was investigated in a case-control study. A total of 42 consecutive women with recurrent spontaneous abortion (three or more consecutive abortions, mean +/- SD: 3.9 +/- 1.1 range 3-8) with no parental chromosome rearrangement or uterine abnormality were studied during the early follicular phase under standardized conditions. Serum concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, androstenedione, testosterone, dehydroepiandro-stenedione, 17-OH-progesterone, oestradiol, progesterone and thyroid stimulating hormone (TSH) were measured by commercially available radioimmunoassays. Controls were 42 nulligravid females with tubal or male factor infertility without miscarriage. Mean (SD) concentrations of prolactin and androstenedione were 14.2 +/- 6.7 ng/ml versus 10.5 +/- 3.5 ng/ml (95% CI 0.8-6.1) and 2.3 +/- 0.9 ng/ml versus 1.7 +/- 0.6 ng/ml (95% CI 0.2-0.9) in the study and control groups respectively. The other endocrine parameters were comparable in both groups. Obesity [BMI weight (kg)/height (m2) > or = 25] was more prevalent (23 versus 5 women, P = 0.0001) in the study than the control group. Recurrent spontaneous abortion is associated with abnormalities in prolactin and androgen secretion during the follicular phase, suggesting an endocrine aetiology in this disorder. Reduction of body weight and correction of hyperprolactinaemia and of hyperandrogenism may reduce the rate of miscarriage in a subsequent pregnancy in these women.     

Lymphocyte Subsets in Habitual Abortion

ABSTRACT: Lymphocyte subpopulations were characterized by means of monoclonal antibodies in 25 women with habitual abortion and 21 muciparous normal women. Compared to nonpregnant women (N = 8), pregnant normal women were associated with significantly lower helper-to-suppressor ratios (1.71 ± 0.41 versus 2.37 ± 0.66). In contrast in pregnant women with habitual abortion (N = 13) the ratio remained high (2.32 ± 0.73). Failure to increase the number of suppressors and a significant rise in helpers caused this increased ratio. We discuss the possible mechanisms and etiological importance of this finding in habitual abortion.     

Suppression of Natural Killer Cell Activity and Interleukin-2 Concentration of Serum Obtained from In Vitro Fertilization-Embryo Transfer Patients

PROBLEM: The effect of serum obtained from in vitro fertilization-embryo transfer (IVF-ET) patients on healthy volunteers' natural killer (NK) cell activity was evaluated. We also measured interleukin (IL)-2 concentration with IVF-ET patients' serum and clarified the relationship between IL-2 levels and the suppressive effect on NK cell activity. METHOD OF STUDY: A retrospective nonrandomized clinical study was performed. The suppressive effect on NK cell activity and IL-2 concentrations was measured with serum obtained from 30 pregnant and 30 nonpregnant women during an IVF-ET procedure. The suppressive effect of the serum on NK cell activity was evaluated by the formula that we defined in our previous study. RESULTS: The suppression of NK cell activity was significantly higher in the nonpregnant women than in the pregnant women (P < 0.05); however, IL-2 concentration did not differ. There was a positive correlation between the suppression of NK cell activity and IL-2 levels in the pregnant women, but no significant correlation in the nonpregnant women. CONCLUSIONS: These results suggest that the suppression of NK cell activity may be one of the prognostic factors for IVF-ET. In addition, we speculate that an unidentified humoral factor other than IL-2, which could increase NK cell activity, might exist in the serum of the nonpregnant patient.     

Pre-conceptional natural killer cell activity and percentage as predictors of biochemical pregnancy and spontaneous abortion with normal chromosome karyotype

PROBLEM: The aim of the present study was to determine whether pre-conceptional natural killer (NK) cell activity and percentage are predictive of subsequent spontaneous abortion in women with recurrent spontaneous abortion (RSA). METHOD OF STUDY: Pre-conceptional NK cell activity and percentage in peripheral blood of women who had a history of two or more RSA was prospectively assessed. The 51Cr release assay and flow cytometric analysis were performed. A total of 113 RSA women were recruited, and 85 conceived later. RESULTS: Pre-conceptional NK cell activity/percentage values in women whose next pregnancies ended in biochemical pregnancy and spontaneous abortion with normal fetal karyotype (n = 17, median 47%/17.1%), but spontaneous abortion with abnormal karyotype (n = 9, 27%/15.7%), were higher than those in live births (n = 59, 33%/13.1%). High values of pre-conceptional NK cell activity (> 46%; relative risk 3.6, 95%CI 1.6-8.0) and percentage (> 16.4%; 4.9, 1.7-13.8) were found to predict biochemical pregnancy and spontaneous abortion with normal karyotype in the next pregnancy. CONCLUSION: Pre-conceptional NK cell abnormalities were predictive of spontaneous abortion with normal fetal karyotype.