Serial study of T-lymphocyte subsets in women during very early pregnancy

Advances in Hepatitis E Virus Biology and Pathogenesis

Hepatitis E virus (HEV) is one of the causative agents for liver inflammation across the world. HEV is a positive-sense single-stranded RNA virus. Human HEV strains mainly belong to four major genotypes in the genus Orthohepevirus A, family Hepeviridae. Among the four genotypes, genotype 1 and 2 are obligate human pathogens, and genotype 3 and 4 cause zoonotic infections. HEV infection with genotype 1 and 2 mainly presents as acute and self-limiting hepatitis in young adults. However, HEV infection of pregnant women with genotype 1 strains can be exacerbated to fulminant hepatitis, resulting in a high rate of case fatality. As pregnant women maintain the balance of maternal-fetal tolerance and effective immunity against invading pathogens, HEV infection with genotype 1 might dysregulate the balance and cause the adverse outcome. Furthermore, HEV infection with genotype 3 can be chronic in immunocompromised patients, with rapid progression, which has been a challenge since it was reported years ago. The virus has a complex interaction with the host cells in downregulating antiviral factors and recruiting elements to generate a conducive environment of replication. The virus-cell interactions at an early stage might determine the consequence of the infection. In this review, advances in HEV virology, viral life cycle, viral interference with the immune response, and the pathogenesis in pregnant women are discussed, and perspectives on these aspects are presented.

Longitudinal study of CD4+ cell counts in HIV-negative pregnant patients

OBJECTIVE

To evaluate the absolute CD4+, CD8+, and lymphocyte cell counts and percentages from the first trimester through 6-12 weeks post-delivery in normal human immunodeficiency virus (HIV)-negative pregnant patients.

METHODS

A longitudinal laboratory analysis was performed during pregnancy that involved 51 HIV-negative subjects with blood analysis obtained in all trimesters, at delivery, and 6-12 weeks post-delivery. Twenty-five HIV-negative non-pregnant controls were also evaluated. Blood was analysed for absolute CD4+, CD8+, and lymphocyte cell counts and percentages. Means, standard deviations, trends, and differences were examined.

RESULTS

The mean white blood cell (WBC) count is elevated above the non-pregnant state and this parameter increases through the pregnancy up to and including parturition. The mean absolute lymphocyte cell count, lymphocyte percentage, and absolute CD4+ cell count are significantly lower during pregnancy and the progression through pregnancy appears U-shaped. The mean absolute CD8+ cell count is not significantly different. The CD4+ and CD8+ percentages are higher during pregnancy and this elevation persists into the 6-12 week post-delivery time period. A 3-digit drop in CD4+ percentage is common during pregnancy between blood draws; whereas, a 30% decrease or more in absolute CD4+ cell count is rare.

CONCLUSIONS

By longitudinal analysis, pregnancy appears to significantly elevate the mean values of the WBC count, CD4+ percentage, and CD8+ percentage, but significantly decreases the absolute lymphocyte count, lymphocyte percentage, and absolute CD4+ cell count when compared to non-pregnant controls. The mean absolute CD8+ cell count appears to be unaffected.

Maternal and early life stress effects on immune function: relevance to immunotoxicology

Stress is triggered by a variety of unexpected environmental stimuli, such as aggressive behavior, fear, forced physical activity, sudden environmental changes, social isolation or pathological conditions. Stressful experiences during very early life (particularly, maternal stress during fetal ontogeny) can permanently alter the responsiveness of the nervous system, an effect called programming or imprinting. Programming affects the hypothalamic-pituitary-adrenocortical (HPA) axis, brain neurotransmitter systems, sympathetic nervous system (SNS), and the cognitive abilities of the offspring, which can alter neural regulation of immune function. Prenatal or early life stress may contribute to the maladaptive immune responses to stress that occur later in life. This review focuses on the effect of maternal and early life stress on immune function in the offspring across life span. It highlights potential mechanisms by which prenatal stress impacts immune functions over life span. The literature discussed in this review suggests that psychosocial stress during pre- and early postnatal life may increase the vulnerability of infants to the effects of immunotoxicants or immune-mediated diseases, with long-term consequences. Neural-immune interactions may provide an indirect route through which immunotoxicants affect the developing immune system. A developmental approach to understanding how immunotoxicants interact with maternal and early life stress-induced changes in immunity is needed, because as the body changes physiologically across life span so do the effects of stress and immunotoxicants. In early and late life, the immune system is more vulnerable to the effects of stress. Stress can mimic the effects of aging and exacerbate age-related changes in immune function. This is important because immune dysregulation in the elderly is more frequently and seriously associated with clinical impairment and death. Aging, exposure to teratogens, and psychological stress interact to increase vulnerability and put the elderly at the greatest risk for disease.

Hepatitis E and pregnancy: understanding the pathogenesis

Hepatitis E virus (HEV) is a single-stranded RNA virus that causes large-scale epidemics of acute viral hepatitis, particularly in developing countries. In men and non-pregnant women, the disease is usually self-limited and has a case-fatality rate of less than <0.1%. However, in pregnant women, particularly from certain geographical areas in India, HEV infection is more severe, often leading to fulminant hepatic failure and death in a significant proportion of patients. In contrast, reports from Egypt, Europe and the USA have shown that the course and severity of viral hepatitis during pregnancy is not different from that in non-pregnant women. The reasons for this geographical difference are not clear. The high mortality rate in pregnancy has been thought to be secondary to the associated hormonal (oestrogen and progesterone) changes during pregnancy and consequent immunological changes. These immunological changes include downregulation of the p65 component of nuclear factor (NF-kappaB) with a predominant T-helper type 2 (Th2) bias in the T-cell response along with host susceptibility factors, mediated by human leucocyte antigen expression. Thus far, researchers were unable to explain the high HEV morbidity in pregnancy, why it is different from other hepatitis viruses such as hepatitis A with similar epidemiological features and the reason behind the difference in HEV morbidity in pregnant women in different geographical regions. The recent developments in understanding the immune response to HEV have encouraged us to review the possible mechanisms for these differences. Further research in the immunology of HEV and pregnancy is required to conquer this disease in the near future.

Hepatitis E and pregnancy: understanding the pathogenesis

Hepatitis E virus (HEV) is a single-stranded RNA virus that causes large-scale epidemics of acute viral hepatitis, particularly in developing countries. In men and non-pregnant women, the disease is usually self-limited and has a case-fatality rate of less than <0.1%. However, in pregnant women, particularly from certain geographical areas in India, HEV infection is more severe, often leading to fulminant hepatic failure and death in a significant proportion of patients. In contrast, reports from Egypt, Europe and the USA have shown that the course and severity of viral hepatitis during pregnancy is not different from that in non-pregnant women. The reasons for this geographical difference are not clear. The high mortality rate in pregnancy has been thought to be secondary to the associated hormonal (oestrogen and progesterone) changes during pregnancy and consequent immunological changes. These immunological changes include downregulation of the p65 component of nuclear factor (NF-kappaB) with a predominant T-helper type 2 (Th2) bias in the T-cell response along with host susceptibility factors, mediated by human leucocyte antigen expression. Thus far, researchers were unable to explain the high HEV morbidity in pregnancy, why it is different from other hepatitis viruses such as hepatitis A with similar epidemiological features and the reason behind the difference in HEV morbidity in pregnant women in different geographical regions. The recent developments in understanding the immune response to HEV have encouraged us to review the possible mechanisms for these differences. Further research in the immunology of HEV and pregnancy is required to conquer this disease in the near future.

Role of sympathetic nerves on early embryonic development and immune modulation of uterus in pregnant mice

To determine the role of sympathetic nerves in the early embryonic development and the immune modulation of maternal uterus during pregnancy, a model of chemical sympathectomy in mice was established by intraperitoneal injection of 6-hydroxydopamine (6-OHDA). The embryonic development and the distribution of maternal uterine immunocytes were investigated during early pregnancy (E1-E9) with methods of histology, immunohistochemistry and ELISA. Our data showed that in the 6-OHDA-treated group, the number of implanted embryos was only 64.4% of that in the control group at E7, and the development of uterine glands and vessels was poor in pregnant mice. In addition, in uterine tissues of 6-OHDA-treated mice, the number of CD8+ T cells increased ten-fold and the concentration of IL-2 increased 3.6-fold at E5. However, no obvious changes to the number of CD4+ T cells and IL-4 were observed. Thus, the CD4+/CD8+ T cells ratio significantly decreased, while the IL-2/IL-4 ratio significantly increased. These findings indicated that the activation of sympathetic nerves might be favorable to fetal survival and development during early pregnancy through influencing on immune function and decidua formation of uterus.

HIV-1: maternal prognosis

Profound modifications in the profile of patients are currently being observed within the epidemic context of AIDS, especially with respect to pauperization and feminization of the disease. The population most frequently affected is in the reproductive age, and among adults aged 18 to 24 years, the ratio is 1 man to 1 woman, a phenomenon occurring uniformly all over the world. One of the main challenges for HIV-1-infected pregnant women and their doctors is the effect of the interaction between HIV infection and pregnancy. The present article is a review of the literature; and its objective is to assess the influence of HIV-1 infection seen from the maternal perspective, with a discussion of immunologic function, maternal prognosis, and the HIV-abortion interface. At present, we cannot conclude that pregnancy has a short-term effect on the evolution of HIV infection, but the concomitance of HIV and pregnancy may adversely affect the prognosis of gestation, especially in view of its frequent association with increased abortion and puerperal morbidity rates.

Mother-to-child transmission of HIV-1: the role of HIV-1 variability and the placental barrier

The acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV), was first described in the United States of America in 1981 [1]. The worldwide spread of HIV has soon been recognized and AIDS has become one of the most alarming infectious diseases of our days. Its impact has been tremendous, high morbidity and mortality has caused a reversal of socioeconomic gains previously recorded in several developing countries, especially those in Sub-Saharan Africa [2]. Epidemiological data about the HIV and AIDS pandemic are updated by the Joint United Nation Programme on HIV/AIDS, UNAIDS (http://www.unaids.org). Their latest report from December 2000 states that in year 2000 approximately 5.3 million people have become newly infected with HIV, of which 2.2 were women and 600,000 children younger than 15 years of age. The estimated number of people living with HIV/AIDS globally is 36.1 million, of which 16.4 million are women and 1.4 million are children younger than 15 years of age. Approximately 25.3 million (70%) of these HIV infected people live in Sub-Saharan Africa, 5.8 million in South- and South-East Asia (15%), and 1.4 million in Latin-America (5%). During year 2000, 3 million people died of AIDS (1.3 million women and 500,000 children younger than 15 years of age). This means that an estimated total of 21.8 million persons have died of AIDS since the beginning of the epidemic, including 4.3 million children younger than 15 years of age.

Immunological markers in HIV-infected pregnant and non-pregnant women

OBJECTIVE

To assess the influence of pregnancy on the course of HIV infection by comparing the behaviour of total lymphocyte counts and lymphocyte subsets (CD4(+) and CD8(+) and their ratio) in a cohort of infected pregnant women.

SETTING

Tertiary referral centre for high risk obstetrics and infectious diseases in pregnancy.

PATIENTS AND METHODS

A prospective study was designed, HIV infected women being enrolled at the beginning of pregnancy and sampled each trimester and in the puerperium. As controls, a group of non-pregnant HIV-infected women, cross-matched for age, risk factors and stage of disease were included and similarly evaluated in the same period.

RESULTS

All the parameters, when longitudinally evaluated, were stable during gestation. Compared with non-pregnant subjects, patients had higher CD4(+) counts at the beginning and increased values of total lymphocytes count and subsets during the puerperium. Antepartum and postpartum risk factors such as drug abuse, smoking, antiretroviral therapy, length of gestation, maternal complications and HIV status of the neonate were not influential on the total lymphocytes counts and subsets.

DISCUSSION

According to this data, pregnancy per se seems to have a negligible influence over the course of HIV infection, at least as far as immune parameters are concerned.

Immunologic activation during pregnancy: serial measurement of lymphocyte phenotype and serum activation molecules in HIV-infected and uninfected women

Immunologic alterations occur during pregnancy, but the effect of pregnancy on HIV infection is controversial. We characterized some of the immunologic alterations with potential to influence HIV disease in 99 infected and 46 uninfected women during pregnancy and up to 6 months post-partum. Immunophenotyping to quantitate the major lymphocyte subsets and determine expression of activation and adhesion molecules on T cells was performed using 3-color staining and laser flow cytometry. Serum neopterin, beta 2-microglobulin, and tumor necrosis factor-alpha (TNF alpha) were quantitated using commercial immunoassays. HIV + pregnant women were compared to uninfected pregnant subjects and to reference ranges established on healthy, HIV-seronegative non-pregnant female controls. Both CD4 and CD8 T cell subsets were increased in HIV-negative pregnant women compared to non-pregnant controls. In HIV-infected pregnant women, CD4 T cells were low and CD8 cells were elevated compared to HIV-negative pregnant and non-pregnant women. Levels of subsets were stable during pregnancy and postpartum in both groups of women. Evidence of peripheral immune activation was found during the later stages of pregnancy. Increases in HLA-DR and CD38 activation antigens on CD8 cells, serum neopterin and beta-2-microglobulin were seen during pregnancy in HIV-negative women. These correlates of immune activation were increased in HIV-infected pregnant women and increased further during pregnancy, paralleling changes seen in uninfected pregnant women. These immunologic alterations may directly or indirectly enhance viral replication, impacting the long-term course of HIV disease.

Lymphocyte subsets and mitogen stimulation of blood lymphocytes in normal pregnancy

PROBLEM

In normal pregnancy the maternal immune system should be directed towards tolerance or suppression in order not to reject the partly foreign feto-placental unit. The aim of this investigation was to find hallmarks of systemic immunosuppression during normal pregnancy.

METHODS

Five healthy primigravidae were examined during pregnancy and postpartum with flow cytometric analysis to define T and B lymphocyte subsets in peripheral blood. In addition, we studied the proliferative response of lymphocytes to mitogens or interleukin-2 (IL-2) alone or in combination with immunomodulating drugs or interleukin-4 (IL-4). The results were compared to healthy, non-pregnant women.

RESULTS

During pregnancy and early puerperium we noted an immune balance in favour of suppression, as measured by increased numbers of T "helper/suppressor" (CD4+CD45RA+) and "suppressor"/effector T cells (CD8+S6F1-), and decreased numbers of T "helper/inducer" (CD4+CD29+), T "helper/memory" (CD4+CD45RO+), killer/effector T cells (CD8+S6F1+), and Natural Killer cells (CD56+), as well as decreased numbers of activated lymphocytes expressing IL-2 receptor (CD25+) and T cells expressing HLA-DR (HLA-DR+CD3+). During pregnancy, lymphocyte proliferation was impaired in autologous serum with concanavalin A (ConA), phytohemagglutinin (PHA), or IL-2. A difference in proliferative response to PHA or IL-2 between cultures with AB serum and autologous serum is suggestive of an immunosuppressor factor in serum during pregnancy. Indomethacin significantly increased lymphocyte proliferation in autologous serum with ConA, indicating PGE2 mediated suppressor activity during pregnancy. Chlorambucil and cimetidine modulated the proliferative response to ConA, indicating an alkylating agent sensitive and a histamine dependent suppressor activity during pregnancy.

CONCLUSIONS

During normal pregnancy, a state of systemic suppression of the maternal immune system seems to be present.

Pattern of HIV viraemia and CD4 levels in relation to pregnancy in HIV-1 infected women

The objective was to study HIV-1 viraemia and CD4 levels during and 6 months after pregnancy. HIV cultures on peripheral blood mononuclear cells (PBMC) and plasma from 225 samples were performed in 90 HIV-1 infected women with 59 continued and 35 terminated pregnancies. P-24 antigen and HIV-DNA were also studied. 34 women originated from European, 44 from African and 10 from other countries while 2 were of unknown origin. HIV was detected in 30% of the plasma cultures from the first trimester and in approximately 50% thereafter. Repeated plasma isolations did not give an indication of HIV activation, nor did the cross-sectional time-to-culture positivity in plasma and in PBMC, PBMC isolation frequencies, HIV-DNA and CD4 levels. The plasma viraemia frequencies were generally higher and the CD4 levels lower in the African women than in the European ones. Six months after delivery there was a significant decrease in the CD4 cell counts compared to delivery, but not when compared to the values during the first or second trimesters. The results showed that HIV activity during pregnancy was relatively stable, followed by indications of resumed activity during the first 6 months after delivery.

Hormonal and pregnancy relationships to rheumatoid arthritis: convergent effects with immunologic and microvascular systems

OBJECTIVE

To review sex hormones and rheumatoid arthritis (RA) and the interrelationships between hormonal, immunological, and vascular systems.

DATA SOURCES

Publications detailing serum sex hormone levels and their HLA interactions, steroidogenesis, pregnancy, and therapeutic uses of sex hormones in RA.

STUDY SELECTION

Controlled studies of sex hormone levels in RA patients not previously treated with glucocorticoids.

DATA EXTRACTION

Mean (+/- SD) serum levels of dehydroepiandrosterone sulfate (DHEAS), testosterone (T), and estradiol (E2).

DATA SYNTHESIS

Mean (+/- SD) levels were collated into tables for women with pre-versus postmenopausal onsets of disease and men. Data were also ordered across all study groups by increasing mean levels of the control subjects. Pooled data were summarized statistically, and major sources of variation between the studies were identified.

CONCLUSIONS

Serum DHEAS, an adrenal androgen, was impressively decreased among women with premenopausal onset of RA. One study showed such deficiency years before disease onset. Serum T was somewhat decreased in the premenopausal onset group, but could be explained by decreased peripheral conversion of the lower levels of adrenal androgens. Women with postmenopausal onset of RA had modestly decreased serum DHEAS levels overall, but no difference in serum T, compared with controls. Male RA cases had consistently decreased serum levels of T, but not of DHEAS. Serum E2 was comparable in all RA versus control groups. The complex biology of pregnancy was interpreted as an example of vital interactions between hormonal, immunological, and vascular systems, as they may relate to the physiopathology of RA. The major age, sex, and hereditable determinants of RA were compared within a composite table of estimated relative risks. Elucidation of the interacting risk factors offers promising avenues of research in this complex disease.

Lymphocyte subsets and autoantibodies in pregnancies complicated by placental disorders

PROBLEM

The survival of the fetoplacental unit might partly depend on down-regulation of rejection reactions. Pathological maternal cellular immune response mechanisms could therefore be of pathogenic importance in pregnancies complicated by placental disorders.

METHOD

A flow-cytometric analysis of T-cell subsets and B-cell, as well as serological tests for anticardiolipin antibodies (aCL), antinuclear antibodies (ANA), and rheumatoid factor (RF) were done on 90 women with complicated pregnancies. The results were compared with that of nonpregnant women (n = 5), and normal pregnant women (n = 5) in the third trimester.

RESULTS

Two women, suffering from severe preeclampsia and eclampsia respectively, had aCL on 12 and 13 units, respectively. ANA occurred in 11 patients with moderate and severe preeclampsia and intrauterine growth retardation. All women had negative RF tests. Within the CD4 T-helper subpopulations, the proportion of suppressor/inducer T-cell population (CD4+CD45RA+) significantly increased, while the memory and helper/inducer T-cells (CD4+CD45RO+ and CD4+CD29+) significantly decreased during normal pregnancy compared to nonpregnant controls. This deviation of CD4 subpopulations was not found, or was less pronounced, in complicated pregnancies. The proportion of cytotoxic T cells (CD8+S6F1+) was significantly reduced during normal pregnancy. This reduction was less pronounced in complicated pregnancies.

CONCLUSION

Systemic immunological deviations toward suppression or decreased activity of the immunological response as seen in normal pregnancies, was not observed in preeclampsia, intrauterine growth retardation, intrauterine fetal death, and abruptio placentae. This lack of suppression or increased T-cell activity may have a primary pathogenic role in some women with a complicated pregnancy, or it may be secondary to the placental disorders.

Effect of betamethasone on maternal, fetal and neonatal rat cellular immunity

OBJECTIVE

We evaluated the effect of maternal administration of betamethasone (0.2 mg/kg per day) on mitogen-induced lymphocyte proliferation and interleukin-2 (IL-2) production by maternal, fetal, and neonatal rat splenic lymphocytes.

STUDY DESIGN

Betamethasone was injected intramuscularly on days 19 and 20 of gestation to timed-pregnant rats (Sprague-Dawley). Fetuses were delivered on day 21 of gestation, or allowed to deliver spontaneously at term (22 days), followed by sacrifice at various intervals after birth. Lymphocyte proliferation was determined by 3H-thymidine incorporation with and without phytohemagglutinin (PHA), and IL-2 by proliferation of IL-2 dependent CTLL-2 cells.

RESULTS

Maternal lymphocytes had higher spontaneous proliferation than lymphocytes from nonpregnant female rats. Betamethasone use resulted in a decrease in PHA-induced lymphocyte proliferation and IL-2 production by maternal lymphocytes. These effects were observed until 4 days after delivery. Significant decreases in these parameters were also seen in 21-day fetuses of betamethasone-treated mothers. These effects were still present 6 days after birth but not at 12 days of age.

CONCLUSION

These findings suggest that, in the rat, exposure to betamethasone during late pregnancy results in marked, but transient decreases in PHA-induced lymphocyte proliferation and IL-2 production in both the mothers and their offspring.

The influence of intravenous immunoglobulin treatment on maternal immunity in women with unexplained recurrent miscarriage

PROBLEM

Recently the protective value of high-dose intravenous immunoglobulin (IVIG) in the treatment of unexplained recurrent miscarriage has been reported to be similar to that of conventional immunotherapy with paternal leukocytes. We examined the effect of IVIG treatment on the cellular and humoral level of maternal immunity to demonstrate the possible mechanism by which IVIG might act to prevent recurrence of pregnancy loss.

METHOD

Eight patients were treated with a 20- to 25-g dose of IVIG every 2 to 3 wk during their first-trimester pregnancies. The development of anti-idiotypic autoantibodies against maternal T-cell receptors, maternal anti-paternal lymphocyte antibodies detected by flow cytometric crossmatch, and changes of maternal lymphocyte subpopulations were monitored before pregnancy and then weekly during IVIG treatment.

RESULTS

Five of eight patients gave birth successfully after IVIG treatment given during the first trimester of pregnancy (success rate: 62.5%). Although we could not demonstrate a general immunological effect of IVIG on maternal immunity in vivo, a few significant changes of immunological parameters were found in some patients.

CONCLUSION

Our results suggest that the effect of IVIG on maternal immunity is not a passive increase of blocking antibody including anti-HLA antibody or modification of maternal T-cell subsets but, more likely, a passive increase of anti-idiotypic antibody against anti-HLA antibody or soluble HLA antigens. However, whether the immunomodulating effect of IVIG is related to its possible mechanism to prevent abortion remains unestablished.

Suppression of cytotoxic T-lymphocyte activity during human pregnancy

We have investigated alterations in Epstein-Barr virus antigen specific cytotoxic T-lymphocyte (EBV-CTL) activity during human pregnancy. EBV-CTL activity was determined by a modified EBV induced B-cell focus regression assay and was expressed in terms of a regression index (IR50), i.e. the initial cell concentration required to achieve a 50%-incidence of regression in EBV-infected cell culture. Increased values of IR50 indicate the suppression of EBV-CTL activity. In 113 human female T-cell leukemia type-I (HTLV-I) non-carriers, the IR50 values (mean +/- S.E.) in non-pregnant, pregnant (the first trimester, second trimester and third trimester of pregnancy) and puerperal women were 10.6 +/- 1.4, 16.1 +/- 1.1 (20.1 +/- 2.0, 14.8 +/- 2.0, 14.6 +/- 1.6), and 12.1 +/- 1.9 respectively. Among HTLV-I carriers, the IR50 values (mean +/- S.E.) were likewise 34.6 +/- 8.0, 87.4 +/- 5.2 (101.7 +/- 6.3, 88.3 +/- 8.4 and 79.5 +/- 9.2) and 39.2 +/- 7.1 respectively. This data demonstrate: 1) EBV-CTL activity was suppressed during pregnancy (P < 0.05), especially in the first trimester (P = 0.0003). 2). In HTLV-I carriers, this suppression was shown in the first trimester (P = 0.0002), in the second trimester (P = 0.0002) and in the third trimester of pregnancy (P = 0.0014) and 3). One month after delivery, this suppression had returned to the non-pregnant level in both HTLV-I non-carriers and HTLV-I carriers. Pregnancy therefore has a suppressive effect on antigen specific cytotoxic T-lymphocyte activity and this effect is amplified in HTLV-I carriers.

The situation in Africa

More than three million women world-wide are infected with HIV, and women will constitute 40% of the new AIDS cases in 1990-1991. Unlike in the industrialized world, HIV in Africa is heterosexually transmitted and thus affects at least as many women as men. Already the leading cause of death in a major African city, HIV may be spreading to rural areas. In spite of improvement in surveillance, under-reporting makes it difficult to project trends, document differences within and between urban and rural areas, and identify at-risk groups. Increasing evidence shows that STDs play a major role in spreading the HIV epidemic. Male-to-female transmission is more efficient owing to factors related to the pathogen and the host. Ulcerative STDs such as chancroid, syphilis and herpes facilitate HIV entry through mucosal discontinuation and recruitment of HIV target cells. The role of non-ulcerative STDs such as gonorrhoeal, chlamydial and trichomonal infections needs further elucidation. Lack of circumcision, traditional healing practices and oral contraceptives may affect the risk of viral transmission, but may not be major or modifiable risk factors. Pregnancy and pregnancy-associated immune alterations do not seem to affect the clinical course of HIV/AIDS in African women or impair immunocompetence. Maternal HIV can adversely affect pregnancy outcome in Africa, causing low birth-weight, prematurity, intrauterine and intrapartum fetal death. The risk for these outcomes is likely to depend on the degree of immunological and clinical deterioration. Breast-feeding does not appreciably increase the risk of HIV transmission to the infant and should be actively promoted in Africa. Control of HIV/AIDS in Africa, in the absence of an effective vaccine, will focus on behavioural changes through health education and condom use. High frequency STD transmitter core groups, mainly prostitutes and their clients, are currently the target of prevention campaigns which are proving to be successful and affordable.

Immunology of pregnancy: towards a unifying hypothesis

The variable findings of hormonal-immunoregulation and the variable cellular and humoral immune responses in pregnancy have been considered in relationship to the physiological response. From such considerations it appears that the peripheral blood lymphocyte/leukocyte response in pregnancy is not important, but rather the local uterine immune response at implantation and throughout pregnancy. It is proposed, and evidence is presented, that a normal allogeneic immune response is initiated at the time of implantation of the blastocyst. This immune response regulates the invasive nature of the trophoblast and initiates the first stage of parturition. The initiation and maintenance of this immune response is based on an interplay between maternal and paternal HLA and trophoblast antigens. In the case of HLA-incompatible donor-recipient blastocyst transplants, a more pivotal role for immunoregulation by trophoblast antigens is proposed. This is because it is considered that the local uterine immune response suppresses the expression of allogeneic HLA. This concept is further developed in terms of haploid HLA suppression on maternal and fetal lymphocytes that cross the placenta. This is considered to allow the interaction of these lymphocytes with each other and explains maternal transfer of cell-mediated immunity.

Relation of maternal CMV viremia and antibody response to the rate of congenital infection and intrauterine growth retardation

Pregnancy outcome after maternal primary CMV infection initiated at different times during gestation was investigated by using the inbred Strain-2 guinea pig model of congenital CMV infection. The highest vertical transmission rates occurred in pups from dams that were initially viremic in late gestation presumably because delivery occurred prior to detectable maternal CMV-specific immune response. In contrast, conceptus loss was highest with maternal CMV infection initiated at conception. Intrauterine resorptions, intrauterine growth retardation, and disseminated neonatal CMV infection with CNS involvement were more frequent in pups born to mothers that were initially viremic prior to rather than after midgestation. Maternal viremia was prolonged and antibody responses were delayed after CMV inoculation in early gestation compared to late gestation. Prolonged maternal viremia plus early gestational virus exposure/infection of the fetus appeared to be associated with the most severe outcome. These findings suggest that the timing of initial maternal viremia and immune responses, the stage of fetal development, and the length of in utero exposure to CMV are important factors in subsequent disease expression and rates of congenital infection.

Immunoregulatory mechanisms present in the maternal circulation during pregnancy

Systemic alterations of the maternal inflammatory and immune system occur during pregnancy. These changes alone are unlikely to be responsible for the acceptance of the fetal semiallograft. Numerous local events at the maternal-fetal interface appear to be more important. The alterations of the maternal inflammatory and immune systems are subtle enough for no significant increase of infections or malignancy to be apparent. However, 75% of women with rheumatoid arthritis are clinically improved during pregnancy. The effects of pregnancy on polymorphonuclear cells are not likely to be responsible because cell function actually appears enhanced in vivo, despite the fact that pregnancy serum is suppressive in vitro. There is no clear evidence for reduction of monocyte/macrophage function during pregnancy, either in vivo or in vitro. It is unlikely that modulation of B cell phenotype or function is responsible because no suppression is noted, either in vivo or in vitro. Selected products of B cells, immune complexes, appear to be reduced during pregnancy. In patients, the reduction in the concentration of complexes may be due to adsorption by the placenta. The importance of this reduction as a causative factor in the improvement of women with rheumatoid arthritis during pregnancy remains to be determined. Natural killer cell cytotoxicity is decreased during pregnancy. This may in part be due to the release of progesterone induced blocking factor. It is also possible that circulating factors, capable of inhibiting IL-2 release or IL-2 function in vivo, might be responsible. Natural killer cytotoxicity can be normalized by incubation with IL-2. It is unclear how the reduction of natural killer cell activity might systematically affect inflammation or immunity in vivo during pregnancy. In vivo delayed type hypersensitivity appears somewhat reduced during pregnancy. This observation appears consistent with the improvement of rheumatoid synovitis, which is also thought to be T cell mediated. T cell function, measured in vitro, generally appears normal. However, most recent studies have employed mitogens, such as PHA, which is not physiological. Subtle defects involving antigen processing or antigen presentation might be missed in this system. These observations suggest that circulating factors might be important in modulating the cell mediated immune system, in vivo, during pregnancy. While anti-HLA-DR antibodies eluted from the human placenta may be effective therapy in patients with rheumatoid arthritis, their occurrence is too infrequent to account for the improvement seen in afflicted patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Mononuclear cell subpopulations in human follicular fluid from stimulated cycles

The study of lymphocyte subsets from human follicular fluid (FF) provides an opportunity to evaluate immunological features of the ovary. We investigated the mononuclear cell subsets in FF and peripheral blood obtained at the time of laparoscopy from ten in vitro fertilization (IVF) patients. Midcycle nonpregnant peripheral blood was used as the control. A marked increase in the proportion of monocytes (CD14+) was observed in FF. Although FF was enriched with CD8+ lymphocytes, a decrease in the proportion of CD4+ lymphocytes was observed. "Memory" T cells in FF, identified by the CD4+ CD45R- phenotype, predominated over "naive" T cells (CD4+ CD45R+) at a ratio of 2:1, which differs from the ratio yielded by control blood samples (1:1). The percentage of activated T cells (CD3+ HLA-DR+ cell) increased significantly in FF. When lymphocyte subsets were studied in the peripheral blood of IVF patients, changes similar to but less significant than those in FF were found. These data support the concept that lymphocytes play an important role in ovarian physiology.

Immunosuppression in pregnant women infected with human immunodeficiency virus

One hundred two pregnant women at high risk of infection with the human immunodeficiency virus (62 who were drug abusers and 40 of Haitian origin) were prospectively examined for immunologic changes during and after pregnancy. Among the 63 human immunodeficiency virus-negative women, levels of CD4+ (helper) cells fell to a nadir at 8 weeks before delivery and rose rapidly just before delivery. The level of CD8+ (cytotoxic/suppressor) cells rose slowly from midpregnancy to delivery. Among the 37 human immunodeficiency virus-positive pregnant women, levels of CD4+ cells fell during pregnancy (except for a transient weak increase just before delivery) and did not recover in the postpartum period. Levels of CD8+ cells were consistently higher in human immunodeficiency virus-positive than human immunodeficiency virus-negative women. Post partum the CD8+ cells in human immunodeficiency virus-negative women stabilized at delivery levels, whereas they increased greatly in human immunodeficiency virus-positive women. The loss of CD4+ cells in human immunodeficiency virus-positive women appeared to be faster during pregnancy than in the postpartum period. These data support the hypothesis that pregnancy may accelerate human immunodeficiency virus-induced depletion of CD4+ cells and increase the risk of acquired immunodeficiency syndrome.

Decreased levels of circulating CD4+ T lymphocytes during normal human pregnancy

Peripheral blood mononuclear cell (PBMC) populations during human pregnancy have been investigated by many authors, although the different results obtained, principally in relation to T cells, are very discrepant. In this study we aimed to exclude all the possible causes of these discrepancies: small sample size; diurnal rhythm of CD4+ T cells; smoking habits; haemodilution which occurs during pregnancy and inappropriate statistical analysis; in order to determine whether gestation has a definite effect on PBMC populations. We found that the percentage of CD4+ T lymphocytes decreases in the first and second trimesters, returns to the non-pregnant level in the third trimester and remains there in the postpartum period. The percentages of CD3+ T lymphocytes run parallel to those of CD4+ while CD8+ T lymphocytes do not vary. The proportion of CD16+ cells, which include mature NK cells, diminishes in the second trimester and this reduction is maintained in the third trimester and the puerperium. No variation was found in the other PBMC studied (CD20+ lymphocytes, CD14+ monocytes and D/DR+ cells). When parity was considered no difference was seen between primiparous and multiparous women in any of the cell populations tested.