Immunologic tests in the evaluation of reproductive disorders: a critical review

Immune modulation of i.v. immunoglobulin in women with reproductive failure

Background

The mechanism of maternal immune tolerance of the semi‐allogenic fetus has been explored extensively. The immune reaction to defend from invasion by pathogenic microorganisms should be maintained during pregnancy. An imbalance between the immune tolerance to the fetus and immune activation to the pathogenic organisms is associated with poor pregnancy outcomes. This emphasizes that the immune mechanism of successful reproduction is not just immune suppression, but adequate immune modulation.

Methods

In this review, the action of i.v. immunoglobulin G (IVIg) on the immune system and its efficacy in reproductive failure (RF) was summarized. Also suggested is the indication of IVIg therapy for women with RF.

Main findings (Results)

Based on the mechanism of the immune regulation of IVIg and following confirmation of the immune modulation effects of it in various aberrant immune parameters in patients with RF, it is obvious that IVIg is effective in recurrent pregnancy losses and repeated implantation failures with immunologic disturbances.

Conclusion

The authors recommend IVIg therapy in patients with RF with aberrant cellular immunologic parameters, including a high natural killer cell proportion and its cytotoxicity or elevated T helper 1 to T helper 2 ratio, based on each clinic's cut‐off values. Further clinical studies about the safety of IVIg in the fetus and its efficacy in other immunologic abnormalities of RF are needed.

HLA gene expression is altered in whole blood and placenta from women who later developed preeclampsia

Preeclampsia is a multisystem disease that significantly contributes to maternal and fetal morbidity and mortality. In this study, we used a non-biased microarray approach to identify dysregulated genes in maternal whole blood samples which may be associated with the development of preeclampsia. Whole blood samples were obtained at 28 wk of gestation from 5 women who later developed preeclampsia (cases) and 10 matched women with normotensive pregnancies (controls). Placenta samples were obtained from an independent cohort of 19 women with preeclampsia matched with 19 women with normotensive pregnancies. We studied gene expression profiles using Illumina microarray in blood and validated changes in gene expression in whole blood and placenta tissue by qPCR. We found a transcriptional profile differentiating cases from controls; 336 genes were significantly dysregulated in blood from women who developed preeclampsia. Functional annotation of microarray results indicated that most of the genes found to be dysregulated were involved in inflammatory pathways. While general trends were preserved, only HLA-A was validated in whole blood samples from cases using qPCR (2.30- ± 0.9-fold change) whereas in placental tissue HLA-DRB1 expression was found to be significantly increased in samples from women with preeclampsia (5.88- ± 2.24-fold change). We have identified that HLA-A is upregulated in the circulation of women who went on to develop preeclampsia. In placenta of women with preeclampsia we identified that HLA-DRB1 is upregulated. Our data provide further evidence for involvement of the HLA gene family in the pathogenesis of preeclampsia.

HLA-C antibodies in women with recurrent miscarriage suggests that antibody mediated rejection is one of the mechanisms leading to recurrent miscarriage

HLA-C is the only polymorphic classical HLA I antigen expressed on trophoblast cells. It is known that higher incidence of C4d deposition on trophoblast cells is present in women with recurrent miscarriage. C4d is a footprint of antibody-mediated classical complement activation. Therefore, this study hypothesize that antibodies against HLA-C may play a role in the occurrence of unexplained consecutive recurrent miscarriage. Present case control study compared the incidence of HLA-C specific antibodies in 95 women with at least three consecutive miscarriages and 105 women with uneventful pregnancy. In the first trimester of the next pregnancy, presence and specificity of HLA antibodies were determined and their complement fixing ability. The incidence of HLA antibodies was compared with uni- and multivariate logistic regression models adjusting for possible confounders. Although in general a higher incidence of HLA antibodies was found in women with recurrent miscarriage 31.6% vs. in control subjects 9.5% (adjusted OR 4.3, 95% CI 2.0-9.5), the contribution of antibodies against HLA-C was significantly higher in women with recurrent miscarriage (9.5%) compared to women with uneventful pregnancy (1%) (adjusted OR 11.0, 95% CI 1.3-89.0). In contrast to the control group, HLA-C antibodies in the recurrent miscarriage group were more often able to bind complement. The higher incidence of antibodies specific for HLA-C in women with recurrent miscarriage suggests that HLA-C antibodies may be involved in the aetiology of unexplained consecutive recurrent miscarriage.

Immunotherapy for recurrent miscarriage

BACKGROUND

Because immunological aberrations might be the cause of miscarriage in some women, several immunotherapies have been used to treat women with otherwise unexplained recurrent pregnancy loss.

OBJECTIVES

The objective of this review was to assess the effects of any immunotherapy, including paternal leukocyte immunization and intravenous immunoglobulin on the live birth rate in women with previous unexplained recurrent miscarriages.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (11 February 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomized trials of immunotherapies used to treat women with three or more prior miscarriages and no more than one live birth after, in whom all recognized non-immunologic causes of recurrent miscarriage had been ruled out and no simultaneous treatment was given.

DATA COLLECTION AND ANALYSIS

The review author and the two co-authors independently extracted data and assessed study quality for all studies considered for this review.

MAIN RESULTS

Twenty trials of high quality were included. The various forms of immunotherapy did not show significant differences between treatment and control groups in terms of subsequent live births: paternal cell immunization (12 trials, 641 women), Peto odds ratio (Peto OR) 1.23, 95% confidence interval (CI) 0.89 to 1.70; third-party donor cell immunization (three trials, 156 women), Peto OR 1.39, 95% CI 0.68 to 2.82; trophoblast membrane infusion (one trial, 37 women), Peto OR 0.40, 95% CI 0.11 to 1.45; or intravenous immunoglobulin, (eight trials, 303 women), Peto OR 0.98, 95% CI 0.61 to 1.58.

AUTHORS' CONCLUSIONS

Paternal cell immunization, third-party donor leukocytes, trophoblast membranes, and intravenous immunoglobulin provide no significant beneficial effect over placebo in improving the live birth rate.

An immunological basis for chronic histiocytic intervillositis in recurrent fetal loss

PROBLEM

Chronic histiocytic intervillositis (CHIV) is a rare type of placental pathology that is associated with reproductive loss at all gestational ages. The aim of the study was to investigate the relationship between the severity of CHIV and the outcome of pregnancy and to compare the immune response between CHIV patients and controls to explore an immunological origin of CHIV.

METHOD OF STUDY

Microscopic slides were reviewed and scored according to a previously published grading system in 30 pregnancies of 22 CHIV patients. Partner-specific mixed lymphocyte reactions, cytotoxic T-lymphocyte precursor frequencies (CTLpf), and anti-HLA antibodies were determined in four patients and seven controls.

RESULTS

Higher CHIV scores are associated with worse pregnancy outcome. CHIV patients demonstrated a higher CTLpf against their partner compared to non-complicated pregnancies (P = 0.03). The CTLpf was extremely high in 75% of the patients. Antipaternal HLA antibodies were only present in 75% of the CHIV patients compared to none of the controls (P = 0.02).

CONCLUSION

CHIV scores seem to be associated with the severity of adverse pregnancy outcome. High antipaternal cellular (T-cell) and humoral (B-cell) response to partner-specific CTLpf and the presence of anti-HLA antibodies directed to the partner suggest an immunologic origin of CHIV.

Beneficial or harmful effect of antipaternal human leukocyte antibodies on pregnancy outcome? A systematic review and meta-analysis

PROBLEM

During pregnancy, antibodies are induced that target the paternal human leukocyte antigens of the semi-allogeneic fetus. The level and presence of these antibodies have been reported increased as well as decreased for a variety of pregnancy complications; the clinical relevance and consequences of these antibodies are not very clear. Therefore, the objective of this review is to determine whether the presence of antipaternal antibodies influences pregnancy outcome.

METHOD

We performed a systematic search of studies that described the effect of antipaternal antibodies on pregnancy complications. The primary outcome was the risk ratio for HLA class I and class II antibodies on pregnancy complications. Furthermore, we calculated the risk for first- and third-trimester complications.

RESULTS

The seventeen studies that were selected for meta-analysis showed high level of statistical and clinical heterogeneity. In the meta-analysis, we found no significant effect of HLA class I or class II antibodies on pregnancy outcome.

CONCLUSION

No consistent conclusions can be drawn from the meta-analysis. Discrepancies in the meta-analysis are the result of different screening techniques, varying time points of screening, and use of incorrect control groups. Furthermore, more detailed analyses of the characteristics and specificity of the antibodies involved are essential.

Secondary recurrent miscarriage and H-Y immunity

BACKGROUND

Approximately half recurrent miscarriage (RM) cases remain unexplained after standard investigations. Secondary RM (SRM) is, in contrast to primary RM, preceded by a birth, which increases the transfer of fetal cells into the maternal circulation. Mothers of boys are often immunized against male-specific minor histocompatibility (H-Y) antigens, and H-Y immunity can cause graft-versus-host disease after stem-cell transplantation. We proposed the H-Y hypothesis that aberrant H-Y immunity is a causal factor for SRM.

METHODS

This is a critical review of the H-Y hypothesis based on own publications and papers identified by systematic PubMed and EMBASE searches.

RESULTS

SRM is more common after the birth of a boy and the subsequent live birth rate is reduced for SRM patients with a firstborn boy. The male:female ratio of children born prior and subsequent to SRM is 1.49 and 0.76 respectively. Maternal carriage of HLA-class II alleles presenting H-Y antigens to immune cells is associated with a reduced live birth rate and increased risk of obstetric complications in surviving pregnancies in SRM patients with a firstborn boy. In early pregnancy, both antibodies against HLA and H-Y antigens are increased in SRM patients compared with controls. Presence of these antibodies in early pregnancy is associated with a lower live birth rate and a low male:female ratio in subsequent live births, respectively. Births of boys are also associated with subsequent obstetric complications in the background population.

CONCLUSIONS

Epidemiological, immunogenetic and immunological studies support the hypothesis that aberrant maternal H-Y immune responses have a pathogenic role in SRM.

Fetal rejection: infertility and immunity

Defective reaction toward fetal alloantigens could result in both recurrent spontaneous abortions (RSAs) and recurrent early pregnancy failures (REPFs), the latter existing in couples with unexplained infertility and multiple failures of implantation after in vitro fertilization embryo transfer. Immunological mechanisms leading to RSA and REPF seem to be different, although both syndromes probably have a genetic background that has not been identified so far. Despite the fact that antiphospholipid syndrome is a well-established cause of repeated pregnancy loss, the role of different autoantibodies existing in RSA and REPF patients needs to be elucidated. Immunotherapy is believed to correct the detrimental immune reactions; however, its real effectiveness and safety for the treatment of distinct forms of pregnancy loss need to be reconsidered.

The impact of anti-HY responses on outcome in current and subsequent pregnancies of patients with recurrent pregnancy losses

Women pregnant with a male fetus often generate cellular and humoral immune responses against male-specific minor histocompatibility (HY) antigens-however, the importance of these responses for pregnancy outcome is unclear. Epidemiologic studies have shown that the birth of a boy compared with a girl prior to a series of miscarriages significantly reduces the chance of a subsequent live birth and pregnancies with boys have an increased risk of placental abruption. This paper aims to review the current knowledge about the impact of anti-HY immunity on pregnancy outcome in terms of miscarriage and placental abruption. Our knowledge primarily comes from studies of the impact on pregnancy outcome of HLA class II alleles known to restrict CD4 T cell mediated anti-HY responses among 358 secondary recurrent miscarriage (SRM) patients and 203 of their children born prior to the miscarriages and investigation of these HLA alleles in 8 patients with recurrent severe placental abruptions. The chance of a subsequent live birth in SRM patients with firstborn boys compared to firstborn girls was significantly lower in women with HY-restricting HLA class II alleles [OR: 0.17 (0.1-0.4), p=0.0001]. Most patients with recurrent placental abruptions had firstborn boys and significantly more of these patients carried HLA haplotypes with HY-restricting class II alleles compared with controls (p=0.009). These findings are strongly indicative of aberrant maternal immune reactions against fetal HY antigens playing a role in recurrent miscarriage and placental abruption. We propose pathogenetic pathways for these conditions that in our view best explain the findings.

Functional HY-Specific CD8+ T Cells Are Found in a High Proportion of Women Following Pregnancy with a Male Fetus1

Recent studies have demonstrated that fetal cells can be detected in the maternal circulation during virtually all human pregnancies. These fetal cells can engraft and may be isolated for many decades after pregnancy, leading to a state that may be maintained by the passage of pregnancy-associated progenitor cells. The clinical consequences of fetal cell microchimerism are unclear but may be potentially detrimental or valuable to the mother. One possibility is the generation of an alloreactive immune response by the mother to antigens expressed by the fetus; for example, the HY protein encoded by the Y chromosome. To test this we have screened a cohort of women with a range of parity histories within 8 yr of their last pregnancy for the presence of an HY-specific CD8+ T-cell response. Fluorescent HLA-peptide (HY) tetramers were used to stain short-term T-cell cultures from these women for analysis by flow cytometry. Responses were detected in 37% of women with a history of pregnancies that produced males, and this value rose to 50% in women with two or more pregnancies that produced males. HY-specific CD8+ T cells also could be detected directly in the peripheral blood of women with a history of at least two pregnancies that produced males. These HY-specific CD8+ T cells produced interferon gamma (IFNG) following peptide stimulation, demonstrating their functional capacity. In conclusion, our data indicate that alloreactive CD8+ T cells are generated frequently following normal pregnancy and retain functional capability for years following pregnancy.

Evidence-based investigations and treatments of recurrent pregnancy loss

PURPOSE OF REVIEW

The majority of investigations and treatments offered to women with recurrent pregnancy loss are not evidence-based. In this review a critical analysis is given of the current management of recurrent pregnancy loss often recommended in meta-analyses and guidelines.

RECENT FINDINGS

Our knowledge of genetic, endocrine, thrombophilic and immunological causes of recurrent pregnancy loss has been improved significantly, primarily by the introduction of modern laboratory techniques. Most clinical trials in this area, however, are still subject to serious methodological flaws.

SUMMARY

At present, the clinician must base their clinical practice on the few high-quality observational studies and intervention trials available rather than on meta-analyses, as there is a scarcity of good clinical trials. More high-quality clinical studies are urgently needed in this area.

Immunological analogy between allograft rejection, recurrent abortion and pre-eclampsia - the same basic mechanism?

There are still controversies concerning the role of immunological mechanisms engaged both in recurrent abortions (RA) and pre-eclampsia (PE). According to some opinions, recurrent miscarriage is comparable to organ-specific autoimmune disease. Analysis of immune reactions shows that graft rejection shares many similar mechanisms with RA and PE. This fact allows us to conclude that rejection of transplanted alloantigenic organs and pregnancy loss have probably the same evolutionary origin. Subsets and functions of immunocompetent cells (T CD4, suppressor gammadeltaT, cytotoxic T CD8, Treg, Tr1, uterine NK cells), over-activation of innate immunity (activation of NK cytotoxic cells, macrophages, neutrophils and complement), changes of Th1/Th2 cytokine balance (IL-2, IL-12, IL-15, IL-18, IFNgamma, TNFalpha vs. IL-4, IL-10, TGFbeta), importance of HLA-G molecule, CD200/CD200R interaction, over-expression of adhesion molecules, fgl2 prothrombinase activation and stimulation of IDO and HO expression, all suggest that RA and PE are syndromes of fetal allograft rejection, and not organ-specific autoimmune diseases. According to that supposition, an analogy might exist between acute graft rejection and recurrent abortion, and between chronic graft rejection and pre-eclampsia.

Immunotherapy for recurrent miscarriage

BACKGROUND

Because immunological aberrations might be the cause of miscarriage in some women, several immunotherapies have been used to treat women with otherwise unexplained recurrent pregnancy loss.

OBJECTIVES

The objective of this review was to assess the effects of any immunotherapy, including paternal leukocyte immunization and intravenous immune globulin on the live birth rate in women with previous unexplained recurrent miscarriages.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2004, Issue 3), MEDLINE (1966 to September 2004) and EMBASE (1980 to September 2004).

SELECTION CRITERIA

Randomized trials of immunotherapies used to treat women with three or more prior miscarriages and no more than one live birth after, in whom all recognised non-immunologic causes of recurrent miscarriage had been ruled out and no simultaneous treatment was given.

DATA COLLECTION AND ANALYSIS

The review author and the two co-authors independently extracted data and assessed study quality for all studies considered for this review.

MAIN RESULTS

Twenty trials of high quality were included. The various forms of immunotherapy did not show significant differences between treatment and control groups in terms of subsequent live births: paternal cell immunization (12 trials, 641 women), Peto odds ratio (Peto OR) 1.23, 95% confidence interval (CI) 0.89 to 1.70; third party donor cell immunization (three trials, 156 women), Peto OR 1.39, 95% CI 0.68 to 2.82; trophoblast membrane infusion (one trial, 37 women), Peto OR 0.40, 95% CI 0.11 to 1.45; intravenous immune globulin, Peto OR 0.98, 95% CI 0.61 to 1.58.

AUTHORS' CONCLUSIONS

Paternal cell immunization, third party donor leukocytes, trophoblast membranes, and intravenous immune globulin provide no significant beneficial effect over placebo in improving the live birth rate.

Evidence-based investigations and treatments of recurrent pregnancy loss

OBJECTIVE

To give an overview of currently used investigations and treatments offered to women with recurrent pregnancy loss (RPL) and, from an evidence-based point of view, to evaluate the usefulness of these interventions.

DESIGN

Ten experts on epidemiologic, genetic, anatomic, endocrinologic, thrombophilic, immunologic, and immunogenetic aspects of RPL discussed methodologic problems threatening the validity of research in RPL during and after an international workshop on the evidence-based management of RPL.

CONCLUSION(S)

Most RPL patients have several risk factors for miscarriage, and an extensive investigation for all major factors should always be undertaken. There is an urgent need for agreement concerning the thresholds for detecting what is normal and abnormal, irrespective of whether laboratory tests or uterine abnormalities are concerned. A series of lifestyle factors should be reported in future studies of RPL because they might modify the effect of laboratory or anatomic risk factors. More and larger randomized controlled trials, including trials of surgical procedures, are urgently needed, and to achieve this objective multiple centers have to collaborate. Current meta-analyses evaluating the efficacy of treatments of RPL are generally pooling very heterogeneous patient populations and treatments. It is recommended that future meta-analyses look at subsets of patients and treatment protocols that are more combinable.

Impact of the sex of first child on the prognosis in secondary recurrent miscarriage

BACKGROUND

The carriage of a male fetus often initiates maternal immunological reactions against male-specific minor histocompatibility (HY) antigens, which, in theory, could result in subsequent recurrent miscarriage (RM).

METHODS

Information about subsequent pregnancy outcome was procured among 182 women with RM after a birth (secondary RM) referred since 1986 using questionnaires, telephone interviews and registers.

RESULTS

Significantly more of the women had had a male first-born as compared with a female first-born (110 versus 72; P < 0.02). By January 2002, 58% of those who had a male first-born had given birth to a second live infant compared with 76% of those who previously had had a female first-born (P = 0.01). Women in the former group had a significantly lower chance of having a second child than those in the latter (adjusted hazard ratio 0.59; 95% confidence interval 0.41-0.86). The number of miscarriages after admission and the risk of secondary infertility were significantly greater in women with a male first-born than among those with a female first-born (P < 0.001 and P = 0.02; respectively).

CONCLUSIONS

A male first-born seems to be associated with a less favourable reproductive potential among women with secondary RM. Maternal immunization against HY antigens may be responsible for these findings.

Active or passive immunization in unexplained recurrent miscarriage

Controversy exists as to whether active immunotherapy with allogeneic lymphocyte transfusions (ALT) or passive immunotherapy with intravenous immunoglobulin (IvIg) improve the chance of live birth in women with unexplained recurrent miscarriages (RM). Meta-analyses of the placebo-controlled trials carried out as Cochrane reviews have concluded than none of the different forms of immunotherapy has proved effective in the total RM population. However, the included trials have generally been small and very heterogenous with respect to the clinical histories of patients and the immunization protocols. Thus, other meta-analyses which have looked at the efficacy in subgroups of RM patients have reported that ALT and IvIg may be effective in women with primary RM and secondary RM, respectively. In RM clinics in Denmark, ALT with donor lymphocytes or IvIg immunotherapy have been tested in several placebo-controlled trials since 1986 in which greater doses than used in other trials have been administered, and both treatments are now used for routine therapy. Our results have convinced us that using the correct immunization protocols on the right subsets of RM patients is effective, but we admit that new placebo-controlled trials focusing on subsets of RM patients are now urgently needed. Furthermore, treated patients should be extensively monitored for changes in a series of immune parameters that may predict pregnancy success and be of importance for our understanding of the mechanisms of action of immunotherapy in RM.

Identification of RANTES as a novel immunomodulator of the maternal allogeneic response

We investigated the immunomodulatory role of chemokines in the maternal allogeneic T-cell response. In comparison with fertile women, we found in patients with recurrent spontaneous abortions (RSA), a significant decreased sera level of RANTES that increased after immunization with paternal leukocytes. Since blocking factors with unknown identity are detected in sera from fertile women, we hypothesized that RANTES might function as a novel blocking factor and therefore we explored its cell growth inhibitory properties during the allogenic T-cell response. We demonstrated that RANTES inhibits the mixed lymphocyte reaction (MLR) in a dose-dependent manner. Investigation of the mechanisms involved in cell growth inhibition revealed that this beta-chemokine induces T-cell apoptosis through modulation of Bcl-2 protein levels and by a caspase-independent mechanism and does not involve modulation of Fas (CD95) antigen expression. Our results provides experimental evidence implicating RANTES as a suppressor of alloantigen specific T-cell responses and indicates that this beta-chemokine might function as a novel blocking factor and reliable marker for successful allotreatment of RSA patients.

Immunotherapy for recurrent miscarriage

BACKGROUND

Immunologic aberrations might be the cause of recurrent early pregnancy loss in some women.

OBJECTIVES

The objective of this review was to assess the effects of leukocyte immunisation or other immunologic treatments such as intravenous immune globulin (IVIG) on the live birth rate in women with previous unexplained recurrent miscarriages.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register was searched (September 2002). Individual patient data were obtained from the American Society for Reproductive Immunology.

SELECTION CRITERIA

Randomised trials of immunotherapy in women with three or more prior miscarriages and no more than one live birth; all recognised non-immunologic causes ruled out and no simultaneous treatment intervention.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed by one reviewer.

MAIN RESULTS

Nineteen trials of high quality were included. The various forms of immunotherapy did not show significant differences between treatment and control groups in terms of subsequent live births: paternal cell immunisation (11 trials, 596 women), odds ratio (OR) 1.05, 95% confidence intervals (CI) 0.75 to 1.47; third party donor cell immunization (3 trials, 156 women), OR 1.39, 95% CI 0.68 to 2.82; trophoblast membrane infusion (1 trial, 37 women), OR 0.40, 95% CI 0.11 to 1.45; intravenous immune globulin (IVIG), OR 0.98, 95% CI 0.61 to 1.58.

REVIEWER'S CONCLUSIONS

Paternal cell immunization, third party donor leukocytes, trophoblast membranes, and intravenous immune globulin provide no significant beneficial effect over placebo in preventing further miscarriages.

Long-term feto-maternal microchimerism: nature's hidden clue for alternative donor hematopoietic cell transplantation?

During pregnancy, fetal hematopoietic cells carrying paternal human leukocyte antigens (HLA) migrate into maternal circulation, and, vice versa, maternal nucleated cells can be detected in fetal organs and umbilical cord blood, indicating the presence of bidirectional cell traffic between mother and fetus. By taking advantage of fluorescence in-situ hybridization or polymerase chain reaction-based techniques, researchers recently found that postpartum persistence of such reciprocal chimerism was common among healthy individuals and may sometimes cause tissue chimerism. Although the biological significance of long-lasting feto-maternal microchimerism is unknown, a number of investigations have suggested its association with the development of "autoimmune" diseases such as systemic sclerosis. However, the very common presence of feto-maternal microchimerism among subjects without any autoimmune attack may allow us the more appealing hypothesis that it is an indicator for the acquired immunological hyporesponsiveness to noninherited maternal or fetal HLA antigens. An offspring's tolerance to noninherited maternal antigens has been clinically suggested by the retrospective analysis of renal transplantations or haploidentical hematopoietic stem cell transplantations, and whether postpartum mothers can tolerate paternally derived fetal antigens is an intriguing question. Although an exact linkage between microchimerism and transplantation tolerance is yet to be elucidated, long-term acceptance of a recipient's cell in the donor may have a favorable effect on preventing the development of severe graft-versus-host disease, and the donor cell microchimerism in the recipient might facilitate the graft acceptance. If this concept holds true, HLA-mismatched hematopoietic stem cell transplantation would be more feasible among haploidentical family members mutually linked with feto-maternal microchimerism. Further studies are warranted to investigate the potential role of feto-maternal microchimerism in human transplantation medicine.

Immunological evaluation of patients with recurrent abortion

In a prospective study, we performed immunological tests in patients with recurrent abortion. Nine couples with two or more fetal losses of no apparent cause were selected as the patient group, and nine volunteer couples with at least two children and without a history of abortion were used as controls. The frequency of major histocompatibility complex (human leukocyte antigens, HLA) antigen sharing was determined by serological methods, antipaternal antibodies by microlymphocytotoxicity, lymphocyte phenotypes (CD4, CD8, CD19, CD16, CD56 and HLA-DR positive cells) by flow cytometry and natural killer (NK) cytotoxicity by (51)Cr release. NK activity was correlated to the degree of HLA-C sharing and to the percentage of CD16+ and CD56+ cells and to progesterone levels measured by radioimmunoassay. No difference in class I or class II HLA antigen sharing was detected between couples with and without recurrent abortion. Antipaternal antibodies were not found in the serum of any woman of the study. A higher absolute number of CD8+ cells (P=0.01) and a trend to increased CD19+ cells (P=0.05) were observed among patients. NK activity did not differ between the two groups when expressed as specific cytotoxicity and it was reduced among patients with recurrent abortion when expressed as lytic units/10(7) cells (P=0.04). There was correlation between NK activity and the percentage of CD16+ and CD56+ cells but not with progesterone levels in patients with recurrent abortion. Our data suggest that an increased NK activity may not play a role in the occurrence of repeated abortion. On the other hand, an increase in circulating CD8+ T cells was observed in patients suggesting that antifetal cytotoxicity in recurrent abortion may be mediated by T cells and not by NK cells.

Risk factors in miscarriage: a review

Miscarriage is one of the most frequent problems in human pregnancy. The most widely accepted definition is that proposed by the World Health Organization (WHO) in 1977. The incidence among clinical pregnancies is about 12-15% but including early pregnancy losses it is 17-22%. The only two etiologic factors recognized by all authors are uterine malformations and parental balanced chromosomal rearrangements. There have been many other suggested risk factors. In this revision we discuss these.

The role of T-helper cytokines in human reproduction

OBJECTIVE

To explore the role of maternal periimplantation endometrial T-helper-1 (TH-1) and T-helper-2 (TH-2) cytokines in the success or failure of human reproduction and their relation to the endocrine system and subsequent pregnancy outcome.

DESIGN

Controlled, prospective study.

SETTING

A tertiary care hospital with a university-based reproductive medicine clinic.

PATIENT(S)

Healthy women and women with recurrent miscarriage who had no history of infertility or autoimmune disease.

INTERVENTION(S)

Measurement of qualitative cytokine expression by RT-PCR and quantitative by ELISA, also hormone levels and pregnancy outcome.

MAIN OUTCOME MEASURE(S)

Expression of TH-1 and TH-2 cytokines and correlation with hormone levels and subsequent pregnancy outcome.

RESULT(S)

Levels of TH-1 cytokines were significantly greater and higher in women with recurrent miscarriage compared with controls, whereas levels of TH-2 cytokine interleukin-6 were significantly lower in women with recurrent miscarriage than in controls. There was no correlation between cytokine expression and serum hormone levels, and periimplantation cytokine levels were not predictive of subsequent pregnancy outcome in women with recurrent miscarriage.

CONCLUSION(S)

This study demonstrated in vivo that women with recurrent miscarriage exhibit primarily TH-1 cytokines, whereas healthy women exhibit decreased TH-1 cytokines and increased TH-2 cytokines. This suggests a potential role for a dichotomous T-helper response in the mediation of subsequent reproductive events. This maternal T-helper response appears to operate independently of hormonal factors in influencing the success or failure of human reproduction, as no correlation was evident between serum hormone levels and cytokine levels. An attempt to use periimplantation TH-1 and TH-2 cytokine profiles as a predictor of subsequent pregnancy outcome (live birth or no live birth) was limited by the small number of patients studied.

Microchimerism and blocking activity in women with recurrent spontaneous abortion (RSA) after alloimmunization with the partner's lymphocytes

Alloimmunization therapy using the partner's leukocytes has been reported to be effective in preventing the failure of pregnancy in patients who have suffered RSA of unknown cause. After alloimmunization, several investigators have reported the presence of blocking factors (BF) in women with successful pregnancies in in vitro assays of lymphocyte response. The recent discovery of small numbers of ubiquitous donor cells (microchimerism) in human transplants up to 29 years post-transplantation has raised questions about the migration of the chimeric cells and their role in the induction and perpetuation of tolerance. We have investigated the production of BF in the mixed lymphocyte reaction (MLR) before and in some patients after alloimmunization and its possible relation with the development of microchimerism (M). Before the treatment we studied 14 couples with three or more abortions who were evaluated clinically to rule-out genetic, structural, endocrine, infectious and autoimmune causes. The M study was done by nested PCR-SSP technique with HLA-DR alleles, before and after 30 days of the last immunization. Before the treatment only one patient was M positive and none were BF positive with inhibition effect (IE) > 50. Only eight underwent treatment. The patients had between three and nine alloimmunizations (x = 4.7). After treatment, all patients were M positive with IE > 50. Six months after the last immunization, four patients are M positive with IE > 50. In conclusion, the hypothesis proposes that alloimmunization establishes a state of microchimerism that would be the necessary allogeneic stimulus for T-cell activation, and the induction or maintenance of tolerance to the fetus during pregnancy. reserved.

The production of MLR-blocking factors after lymphocyte immunotherapy for RSA does not predict the outcome of pregnancy

PROBLEM

The questions of whether production of mixed lymphocyte reaction-blocking factors (MLR-BFs) after immunotherapy with lymphocytes for recurrent spontaneous abortion (RSA) has prognostic value and whether cytotoxic antibodies are also involved were tested.

METHOD OF STUDY

A prospective study with 33 patients who had a history of two or more abortions, lacking MLR-BFs, was carried out. The patients received immunizations with lymphocytes and 6 weeks or later were tested for seroconversion of MLR-BFs. Seventeen of these thirty-three patients were evaluated for antipaternal cytotoxic antibodies. The results were correlated with the outcome of the next pregnancy after treatment.

RESULTS

Eighty percent of the 33 patients had a live child. Of those patients having success, only 50% produced MLR-BFs. Of those patients having a new loss, five did and two did not produce MLR-BF (P > 0.05). Regarding the 17 patients tested for cytotoxic antibodies, 4 of the 5 patients who tested positive had a new abortion, whereas only 1 of 12 whose tests remained negative did not have gestational success (P < 0.01).

CONCLUSION

The presence of MLR-BFs is not a prognostic criterium for the outcome of pregnancy after alloimmunotherapy, and, consequently, it is not a good diagnostic tool for RSA of alloimmune cause.

Intravenous immunoglobulin in the prevention of recurrent spontaneous abortion: the European experience

PROBLEM

Clinical trials of the use of intravenous immunoglobulin (IvIg) in the treatment of recurrent spontaneous abortion (RSA) in Europe were reported and discussed.

METHOD OF STUDY

A search of the published literature, combined with our own published and unpublished results, was performed.

RESULTS

Two placebo-controlled trials have been concluded in Europe. One trial found high but equal success rates in both the IvIg and the placebo group. Another trial found that IvIg treatment may increase the success rate by 24% compared with placebo but that the result was not statistically significant, which might be due to the small number of patients. Reasons for the diverse results of the two trials were discussed.

CONCLUSION

More and larger placebo-controlled trials of IvIg treatment in RSA are needed before drawing definitive conclusions.

Inhibitory serum factor of lymphoproliferative response to allogeneic cells in pregnancy

INTRODUCTION

An inhibitory serum factor of mixed lymphocyte culture (MLC) has been associated with successful pregnancy after lymphocyte transfusion in women with unexplained recurrent spontaneous abortions (RSA).

OBJECTIVE

Investigate whether the inhibitory serum factor of MLC is essential for a successful pregnancy.

METHOD

Sera from 33 healthy pregnant women and from 40 women with RSA were assessed by a one-way MLC in which the woman's lymphocytes were stimulated with her partner's lymphocytes or with third party lymphocytes.

RESULTS

An inhibitory serum effect (inhibition > 50% as compared to normal serum) was detected in 45% of the pregnant women who had at least 1 previous parity, in 8% of the primigravidea, in 29% of those with one abortion and in 58% of those with more than one abortion.

CONCLUSION

MLC inhibitory serum factor does not seem to be an essential factor for pregnancy development. Therefore, it should not be considered as a parameter for the assessment of RSA patients.

Immunotherapy for recurrent pregnancy loss: analysis of results from clinical trials

PROBLEM

Up to 80% of unexplained recurrent spontaneous abortions (RSA) are thought to have an immunologic mechanism. Yet clinical trials using immunotherapy to treat women experiencing RSA have low treatment effects. The present study was undertaken to explain the low treatment effects.

METHODS

Results of clinical trials using allogeneic leukocyte immunization and intravenous (IV) immunoglobulin (Ig) are compared. The mechanisms of pregnancy loss are reviewed in light of data on frequency of karyotype abnormalities in trophoblast of failing pregnancies.

RESULTS

Results of two independent analyses using allogeneic leukocyte immunization as immunotherapy for all women with RSA revealed live birth ratios of 1.16 (P = 0.03) and 1.21 (P = 0.02). When the analysis was limited to primary aborters, the live birth ratio increased to 1.46 (P = 0.006). Live birth ratio after immunotherapy for all RSA using IVIg was 1.88 (P = 0.04). Because of low treatment effects, confounders to treatment success of maternal age and number of previous abortions were studied. Chromosomal abnormalities have been identified in 55% of concepti from RSA. The frequency of chromosomal abnormalities remained constant for up to six pregnancy losses. Women with a history of primary compared to secondary RSA had a higher frequency of karyotypically abnormal concepti (chi 2 = 4.54, P < 0.05). Risk factors for RSA also include number of previous losses.

CONCLUSION

Chromosomal abnormalities are a significant confounder when evaluating efficacy of immunotherapy for treatment of RSA. Some women with RSA have a high risk of recurrent chromosomal problems.

HLA sharing, anti-paternal cytotoxic antibodies and MLR blocking factors in women with recurrent spontaneous abortion

OBJECTIVE

To study the prevalence of HLA sharing between spouses and its correlation with presence of antipaternal cytotoxic antibody (APCA) and mixed lymphocyte reaction (MLR) blocking factors in recurrent spontaneous aborters (RSA).

DESIGN

Study was carried out at Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGI), Lucknow, from 1988-1992. Hundred couples with 3 or more consecutive recurrent spontaneous abortions and equal number of age, parity and ethinically matched normal controls were selected for studying HLA, APCA and MLR blocking factors. Meta-analysis was performed using standard formula and significance was tested by Chi-square analysis.

RESULTS

Significant HLA sharing was observed in couples with RSA at A and DR loci compared to normal controls (p < 0.001). Twenty-seven point eight percent of couples with RSA were positive for APCA compared to 49% of controls (p < 0.01). MLR blocking factors were detected in 26% couples with RSA compared to 78% in controls (p < 0.001). An inverse correlation between HLA sharing and APCA and MLR positivity was demonstrated.

CONCLUSION

The study supports that greater HLA sharing between spouses, associated with lack of an appropriate immune response to them could be responsible for RSA.

Flow-cytometric characterization of hematopoietic cells in non-pregnant human endometrium

PROBLEM

Immunologic evaluation and quantitation of hematopoietic cells in human endometrium has been difficult to perform, particularly in nonpregnant subjects. In this study, we describe a method for the flow-cytometric characterization of hematopoietic cells present in the endometrium of non-pregnant women.

METHOD

Endometrial biopsy samples from normal donors were first mechanically disrupted and filtered to generate a single-cell suspension of leukocyte-enriched endometrial cells. Cells were labeled with a panel of monoclonal antibodies, stained with propidium iodide (PI), and one- or two-color flow-cytometric analysis performed on cells excluding PI.

RESULTS

The methodology described in this study was highly reproducible in experiments evaluating the interrun and intrarun variability. We then determined the immunophenotypic profile of endometrial leukocytes from 12 normal females. The majority of leukocytes were T cells (CD3: 47%; CD4: 24%; CD8: 28%) with an important contingent of NK cells (CD56: 32%), the majority of which harbored the unusual CD16-CD56 bright phenotype, and a minority of B cells (CD20: 6%) and monocytes (CD14: 7%).

CONCLUSIONS

Flow cytometry can be used to assess antigen expression on the surface of endometrial leukocytes from nonpregnant women. In future studies, it will be possible to use this approach to investigate the role of immune cell populations in the endometrium of patients experiencing reproductive failure.

Preconceptional natural-killer-cell activity as a predictor of miscarriage

There is no immunological test for the prospective identification of alloimmune causes of miscarriage. We investigated whether activity of natural killer cells was predictive of subsequent abortion in women who had had unexplained recurrent abortions and had received no treatment. 24 women with high preconceptional NK activity, defined as mean plus 1 SD of NK activity of 47 controls, had a significantly higher abortion rate in the next pregnancy than 44 women with normal levels of NK activity (71 vs 20%; relative risk 3.5; 95% CI 1.8-6.5). The preconceptional evaluation of NK activity in women with recurrent miscarriages may thus be predictive of the risk of pregnancy loss at the next conception.

Fertility among women with recurrent spontaneous abortions--the effect of paternal cell immunization treatment

PROBLEM

The risk of women whose chief complaint is recurrent spontaneous abortions (RSA) for secondary infertility (infecundability) has not been evaluated prospectively. The effect of paternal mononuclear cell immunization on conception rates is unknown.

METHOD

Two hundred women whose chief complaint was RSA were randomly assigned to be immunized with paternal mononuclear cells either before or after (up to 6 postmenstrual weeks) conception. Fertility rates (both conception and live birth) were evaluated for the group immunized before conception and compared to those for the control group, who were not immunized until after conception, using life table and multiple logistic regression analyses.

RESULTS

Prospectively ascertained, age-related conception rates for nonimmunized RSA controls appeared to be similar to those for general populations. Immunization before pregnancy had no significant effect (power +/- 14%) on rates of conception (66% before, 77% after) or time to conceive (median weeks before 19.5, after 27.0). Live birth rates (before 59%, after 63%) were also similar for both groups (P = 0.7).

CONCLUSION

Women whose only prior complaint was RSA were not at high risk for secondary infecundability, and immunization did not alter either conception rates or time to conceive. Postponement of immunization until after conception did not affect live birth rates for women selected for study because they did not have a history of prior infecundability or early repeated miscarriages.