The effects of crude and purified human gonadotropin on in vitro stimulated human lymphocyte cultures

Human chorionic gonadotropin as a model for a fetal antigen

Human chorionic gonadotropin (hCG) has an important biological function and has clinical use as a hormone, yet its applications as an antigen are also numerous. Pregnancy tests have brought immunological reactions into the high street pharmacy and the home. As a secreted antigen hCG provides for choriocarcinoma of gestational or germ cell origin our closest approximation to the ideal tumour marker. It is unique in providing the basis of a biochemical screening test for a specific cancer in a high risk population. It has a valuable role in diagnosis and prognosis and in monitoring this disease and detecting tumours is unknown. It has been investigated as a target for radioimmunolocalization studies with 131I-labelled anti-hCG antibodies, and found useful in some patients. Attempts have been made to improve the technique using liposomes containing a second antibody. As a target for antibody therapy in fertility control and oncology, by active or passive immunization methods, much depends on whether hCG functions as a cell membrane antigen.

Chorionic gonadotropin has a recent origin within primates and an evolutionary history of selection

Chorionic gonadotropin (CG) is a critical signal in establishing pregnancy in humans and some other primates, but this placentally expressed hormone has not been found in other mammalian orders. The gene for one of its two subunits (CG beta subunit [CGbeta]) arose by duplication from the luteinizing hormone beta subunit gene (LHbeta), present in all mammals tested. In this study, 14 primate and related mammalian species were examined by Southern blotting and DNA sequencing to determine where in mammalian phylogeny the CGbeta gene originated. Bats (order Chiroptera), flying lemur (order Dermoptera), strepsirrhine primates, and tarsiers do not have a CGbeta gene, although they possess one copy of the LHbeta gene. The CGbeta gene first arose in the common ancestor of the anthropoid primates (New World monkeys, Old World monkeys, apes, and humans), after the anthropoids diverged from tarsiers. At least two subsequent duplication events occurred in the catarrhine primates, all of which possess multiple CGbeta copies. The LHbeta-CGbeta family of genes has undergone frequent gene conversion among the catarrhines, as well as periods of strong positive selection in the New World monkeys (platyrrhines). In addition, newly generated DNA sequences from the promoter of the CG alpha subunit gene indicate that platyrrhine monkeys use a different mechanism of alpha gene expression control than that found in catarrhines.

Molecular architecture and biorecognition processes of the cystine knot protein superfamily: part I. The glycoprotein hormones

In this review article, the reader is introduced to recent advances in our knowledge on a subset of the cystine knot superfamily of homo- and hetero-dimeric proteins, from the perspective of the endocrine glycoprotein hormone family of proteins: follitropin (FSH), Iutropin (LH), thyrotropin. (TSH) and chorionic gonadotropin (CG). Subsequent papers will address the structure-function behaviour of other members of this increasingly significant family of proteins, including various members of the transforming growth factor-beta (TGF-beta) family of proteins, the activins, inhibins, bone morphogenic growth factor, platelet derived growth factor-beta, nerve growth factor and more than 35 other proteins with similar topological features. In the present review article, specific emphasis has been placed on advances with the glycoprotein hormones (GPHs) that have facilitated greater insight into their physiological functions, molecular structures and most importantly the basis of the molecular recognition events that lead to the formation of hetero-dimeric structures as well as their specific and selective recognition by their corresponding receptors and antibodies. Thus, this review article focuses on the structural motifs involved in receptor recognition and the current techniques available to identify these regions, including the role of immunological methodology, peptide fragment design and synthesis and mutagenesis to delineate their structure-function relationships and molecular recognition behaviour.

Growth-stimulating influence of human chorionic gonadotropin (hCG) on Plasmodium falciparum in vitro

In this study, it is reported that human Chorionic Gonadotropin (hCG), being one of the most important hormones of pregnancy, has a growth-stimulating effect on the asexual stages of Plasmodium falciparum in vitro. On the one hand, it is shown that the effect of the hormone is dose-related: The highest growth-rates of Plasmodium falciparum in vitro are achieved, when doses of 8.32 i.u./ml (= 50 i.u. hCG/6 ml) and 16.67 I.U./ml (= 100 i.u. hCG/6 ml) are added to the culture medium. These doses correspond to the physiological peak amounts of hCG between the 9th and 16th week of pregnancy, when parasitaemia also reaches its highest rate. On the other hand, it is shown, that any growth-stimulating effect disappears after inactivation of the hormone by heating at 120 degrees C for 20 minutes. These data support the hypothesis, that hCG does not only possess immunosuppressive properties acting on the response of T-lymphocytes, but also increases the growth of Plasmodium falciparum in vitro. The combination of both effects may explain why malaria still remains one of the most serious complications of pregnancy.

Effects of a urinary factor from women in early pregnancy on HIV-1, SIV and associated disease

The effects of clinical grade crude preparations of human chorionic gonadotropin (hCG) on Kaposi's sarcoma, HIV, SIV and hematopoiesis were examined in vitro and in vivo. In contrast to previous studies, we report that the antiviral activity of hCG associated factors is not due to the native hCG heterodimer, including its purified subunits or its major degradation product, the beta-core. Using gel permeation chromatography of the clinical grade hCG and urine concentrates from pregnant women, we demonstrate that an as yet unidentified hCG associated factor (HAF) with anti-HIV, anti-SIV, anti-KS and pro-hematopoietic activities elutes as two peaks corresponding to 15-30 kDa and 2-4 kDa.

Lymphocytes from pregnant women express human chorionic gonadotropin/luteinizing hormone receptor gene

Previous studies have indicated that human chorionic gonadotropin (hCG) has immunoregulatory properties and alters the functions of human lymphocytes. However, it has not been determined whether the gene encoding the receptors for hCG/luteinizing hormone (LH) is expressed in human lymphocytes. Total peripheral mononuclear lymphocytes isolated from blood samples of pregnant women by Ficoll-Paque gradient centrifugation contained mRNA transcripts encoding the hCG/LH receptors and a 50 kDa receptor protein which can bind 125I-hCG. T-Lymphocytes isolated from total mononuclear cell fractions also contained these receptor mRNA transcripts as well as the receptor protein. The levels of receptor transcripts and receptor protein are lower in lymphocytes than in ovarian tissue. These findings suggest that the immunoregulatory actions of hCG are probably mediated by specific receptors in T-lymphocytes from pregnant women.

Immunosuppressive 30-kDa protein in urine of pregnant women and patients with trophoblastic diseases

Urine samples obtained from normal pregnant women and patients with trophoblastic diseases contain 30-kDa protein that suppresses phytohemagglutinin-induced T cell proliferation. The immunosuppressive protein was measured by a newly developed radioimmunoassay. The 30-kDa protein was demonstrated in almost all urine samples examined, fluid from hydatid vesicles and chorionic extracts, but not in any serum samples except at low levels in some sera from patients with choriocarcinoma. During pregnancy, the level of urinary 30-kDa protein was higher in the first (1625.5 +/- 1212.0 ng/ml, mean +/- S.D.) and second (1457.4 +/- 1332.4 ng/ml) trimesters than in the third trimester (460.6 +/- 419.0 ng/ml). The urinary 30-kDa protein/hCG ratios in patients with choriocarcinoma (8.3 +/- 10.9) were significantly higher than those in patients with hydatidiform mole (0.67 +/- 1.00, P < 0.01) and in all trimesters than those of normal pregnant women (0.54 +/- 0.44 in first trimester, P < 0.05; 0.63 +/- 0.46 in the second trimester, P < 0.05; 0.24 +/- 0.17 in the third trimester, P < 0.01). There is no significant difference between the ratios in hydatidiform mole and normal pregnancy. These findings and the fast disappearance of the 30-kDa protein from the circulation suggest that the 30-kDa protein plays a part in proliferation of trophoblastic cells in, or their invasion into the host by locally suppressing the immune reaction of the host and that the increase in the urinary 30-kDa protein level, in cases of choriocarcinoma, may be due to the malignant transformation of trophoblastic cells resulting in their rapid invasion.

Study on nonspecific immunity in pregnant women: II. Effect of hormones on chemiluminescence response of peripheral blood phagocytes

To analyze the mechanisms of increased nonspecific immunity in pregnant women, the effect of various hormones on the phagocytic activity was estimated by a luminol-dependent chemiluminescence (CL) response during phagocytosing opsonized zymosan. The CL response of whole blood supplemented with exogenous human chorionic gonadotropin (hCG) increased significantly in all the male and female subjects and pregnant women. An approximate two- to fourfold increase was observed in comparison with the unsupplemented control in each subject at concentrations ranging from 1 to 1,000 IU/ml after 48 h of incubation (P less than 0.05). Progesterone slightly stimulated the CL response in female subjects only, but had no effect on male and pregnant women. Estradiol (E2) did not stimulate the CL response in any subject. The expression of Fc and C3b receptors on the surface of polymorphonuclear leucocytes (PMNL) in pregnant women was also investigated by measuring the immunofluorescence stained with monoclonal antibody to Fc and C3b receptors, respectively. The relative numbers of Fc receptors increased significantly in the third trimester compared to those of female control (P less than 0.05). Those of C3b receptor also increased in the second and third trimester (P less than 0.005). These results suggested that the nonspecific immunity represented by phagocytic activity in pregnant women increased with both oxidative metabolic responsiveness and the expression of membrane receptors. Besides, the increased phagocytic activity of the maternal host is probably due to the stimulatory effect of both endogenous and exogenous hCG on their peripheral blood phagocytes.

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)

A comparison between the composition of maternal peripheral plasma and plasma collected from the retroplacental compartment at caesarean section. A study on protein and steroid hormones and binding proteins

In the pregnant uterus unique immunological conditions must prevail. Since compounds of possible fetoplacental origin may modulate the local maternal immunological response, higher concentrations of such compounds in the vicinity of the conceptus might be expected. We have measured the concentrations of several compounds in peripheral and retroplacental plasma, mainly by immunological methods, from women delivered by caesarean section in pregnancy week 38-40. Significantly higher (P less than 0.001) retroplacental concentrations were found for human placental lactogen, prolactin, alpha-fetoprotein, tissue polypeptide antigen, non-conjugated estriol and progesterone. Peripheral plasma levels were significantly higher for cortisol (P less than 0.01), transcortin (P less than 0.001) and sex-hormone binding globulin (P less than 0.002). No difference was found for albumin, alpha 2-macroglobulin, estradiol, placental alkaline phosphatase and human chorionic gonadotrophin. Significant correlations between retroplacental and maternal peripheral plasma levels were found for progesterone, cortisol, estradiol, estriol, transcortin, sex-hormone binding globulin, prolactin, human placental lactogen, human chorionic gonadotrophin, placental alkaline phosphatase, albumin and alpha 2-macroglobulin. There were also significant correlations between estradiol and sex-hormone binding globulin as well as transcortin in peripheral maternal plasma.

Heterogeneity of proteins in commercial preparations of human chorionic gonadotropin (hCG) demonstrated by Western blotting

Immunoblotting has been utilized to detect the presence of human chorionic gonadotropin (hCG), its alpha and beta subunits, the Tamm-Horsfall protein (uromodulin), immunoglobulins G (IgG) and M (IgM), kappa (K) and lambda (L) chains, and serum albumin in commercially available preparations of hCG intended for human use. Concentrated pregnancy, postpartum, and normal urines were studied as a comparison. Those hCG batches prepared from pooled first-trimester pregnancy urine contained all of the hCG and non-hCG proteins listed above or their fragments, with the single exception of the IgM mu chain. The conflicting literature regarding the immunomodulatory properties of hCG requires reevaluation, since many previous reports of immunologic activity utilized these preparations, containing intact and degraded IgG, K, and L chains, and the Tamm-Horsfall protein, all of which may contribute to an altered immune response. Since hCG can be prepared in high yields, free of these contaminants, these data suggest that patients are being unnecessarily exposed to contaminating substances when receiving parenteral injections of hCG.

Study on nonspecific immunity in pregnant women: increased chemiluminescence response of peripheral blood phagocytes

The total number of circulating leucocytes in the peripheral blood of pregnant women progressively increased with advance in gestation because of neutrophilia. When the phagocytic activity, representing nonspecific immunity, was estimated by a luminol-dependent chemiluminescence (CL) response during phagocytosing opsonized zymosan, we observed that the CL response of whole blood and Ficoll-Paque separated polymorphonuclear leucocytes (PMNL) significantly increased throughout the pregnancy (P less than 0.01). The CL responses of mononuclear leucocytes (MN) and monocytes also increased and reached peak levels in the third trimester (P less than 0.05). These findings suggest that the phagocytic activity in pregnant women increases, not only with regard to the number of phagocytes but also with regard to individual cell function, from a relatively early stage of the pregnancy, and that this increased nonspecific immunity may compensate in part for a weakened specific immunity of the maternal host. Attention should be directed to effects of human chorionic gonadotropin (hCG) relative to the increased CL response during pregnancy.

Detection of early pregnancy factor-like activity in women with gestational trophoblastic tumors

The presence of immunosuppressive early pregnancy factor (EPF) in the maternal serum has so far been associated with gestation. Its presence in the serum of women with gestational trophoblastic tumors was investigated. The results indicate that while EPF activity was detected in the serum of women with choriocarcinoma, no such activity was detected in the serum of women with hydatidiform mole, leading to the novel use of EPF as a marker to distinguish these two clinical situations. Results of the experiments also suggest that EPF moiety present in the maternal serum during pregnancy may be of different molecular entity than that present in the serum of women with choriocarcinoma.

Uromodulin, an immunosuppressive protein derived from pregnancy urine, is an inhibitor of interleukin 1

Uromodulin, an 85-kDa glycoprotein isolated from pregnancy urine, has been shown to inhibit antigen-induced proliferation of human lymphocytes in vitro. The present investigation was undertaken to determine its mechanism of action. Uromodulin was found to be a potent inhibitor of interleukin 1 (IL-1)-induced thymocyte proliferation. Uromodulin was compared to a previously described 30- to 35-kDa IL-1 inhibitor isolated from urine of febrile patients (febrile inhibitor). Uromodulin and the febrile inhibitor blocked the effects of both human IL-1 and recombinant murine IL-1, but the activity of uromodulin was greater than that of the only partially purified febrile inhibitor preparation. However, in contrast to the febrile inhibitor, uromodulin markedly enhanced interleukin 2-induced thymocyte proliferation. Antigenic analysis of the two preparations by ELISA and immunoblot analysis demonstrated that the febrile inhibitor did not cross-react with uromodulin using monoclonal or polyclonal antisera. These findings indicate that uromodulin is a potent IL-1 inhibitor that is probably distinct from the IL-1 inhibitor derived from the urine of febrile individuals. Whether this IL-1 inhibitory activity underlies its immunosuppressive activity on human lymphocytes remains to be established.

Immunologic mechanisms in the maternal-fetal relationship

Until recently, the immunologic tolerance between a mother and her allogeneic fetus has been a highly speculative and poorly understood phenomenon. New data indicate that maternal acceptance of the fetal allograft necessitates a specific, protective immune response. This specific recognition apparently involves unique placental antigens with genes that are closely linked to HLA loci. Lack of recognition of these antigens, as in matings between partners with similar HLA profiles, may result in repeated spontaneous abortions caused by unsuppressed rejection mechanisms.

Differential effect of human chorionic gonadotrophin on lymphocyte proliferation induced by mitogens

Human chorionic gonadotrophin (hCG) inhibits the lymphoproliferative responses of human peripheral blood mononuclear cells (PBM) to phytohaemagglutinin (PHA) and concanavalin A (Con A) at 10-50 IU of hCG/ml (P less than 0.05). hCG inhibited poorly the response of PBM to pokeweed mitogen (PWM) at concentration up to 100 IU/ml. When monocytes were removed from the PBM population with columns of Sephadex G10 the inhibitory effect of hCG on PHA- and Con A-induced lymphoproliferation was reduced, with inhibition occurring only at a level of 100 IU of hCG/ml. These results suggest that hCG does not inhibit equally the proliferative response of all lymphocyte subsets and further that cells of the monocyte/macrophage series may play a role in its action on lymphocyte proliferation.

Pregnancy-associated growth factor. I. A proliferative agent which expands adult and cord T4 cells in unfractionated cultures

Experiments were designed to examine the effects of pregnancy-associated growth factor (PAGF), a substance found in commercial preparations of crude human chorionic gonadotropin (hCG), on unfractionated human cord blood cells (CBC) and adult peripheral blood lymphocytes (PBL) cultured in 5% fetal calf serum (FCS). Comparisons of PAGF-induced [3H]TdR incorporation in nine pairs of simultaneously cultured CBC and PBL with phytohemagglutinin (PHA) and tetanus toxoid (TT) showed that all CBC and PBL responded to PAGF and PHA whereas all PBL and one CBC responded to TT. The rank order of potency for CBC and PBL was PHA greater than PAGF greater than TT. To examine phenotypic changes induced by PAGF, flow cytometry was performed on precultured cells, control cultures, and PAGF-stimulated cultures at 2, 5, 7, and 9 days. The monoclonal antibodies (mAbs) included T3, T4, and T8 (T cells), T9 (transferrin receptor), Tac (IL-2 receptor), 12 (Ia or DR-framework antigen), and T10 (putative activation and/or maturation antigen). PAGF-stimulated cultures had statistically significant increased percentages of T3, T4, T9, T10, and Tac but not T8 when compared to precultured cells and control cultures. PAGF also increased PBL but not CBC Ia. In PAGF-stimulated cultures, CBC had more T3 and T4 cells with increased fluorescence intensity than PBL. Maximal expression of phenotypes usually occurred at Days 7 and 9, 2 days after maximal [3H]TdR incorporation. In comparison to PAGF, PHA-stimulated PBL had earlier expression of these phenotypes but included T8. These data indicate PAGF induces proliferation, activation antigens, and T3 expansion predominantly confined to the T4 subset in both CBC and PBL.

Effects of placental extracts on the immune response to histocompatibility antigens: class deviation of alloantibody response and allograft enhancement

Placental extracts obtained from CBA (H-2k) mice during syngeneic (CBA female X CBA male) pregnancy were evaluated for their capacity to deviate the immune reaction of CBA mice toward A/J(H-2a) immunizing spleen cells, as tested by alloantibody subclass formation and Sa 1 allograft accelerated rejection-or enhancement. The immunomodulatory activity appeared to be located in the soluble and in the insoluble extracts of placenta. The sodium deoxycholate (SDO) solubilized proteinic material, fractionated on Concanavalin A [Con A] and injected to CBA mice simultaneously with A/J spleen cells caused a suppression of the hemagglutinating titer and C-mediated cytotoxicity (IgG2). However, it also favoured antibody-mediated mast cell degranulation (IgG1) and Sa 1 allograft enhancement. The presence and role of IgG1 antibodies in both tumor enhancement and gestation has been described. It is concluded that placenta contains Con A-binding glycoproteins which are located in the membranes and released in soluble form. They exert their immunomodulatory effect in a way which might help the successful outcome of pregnancy as it helps to enhance the development of allografted sarcoma.

Correlation of plasma hormone levels and peripheral circulating lymphocyte subpopulations during human pregnancy

Using monoclonal antibodies (OKT3, OKT4, OKT8) peripheral blood lymphocyte subsets were determined in 40 normal primiparous pregnant women and compared with those of 31 nonpregnant controls. In pregnant women plasma concentrations of estradiol, progesterone, human placental lactogen (HPL), beta subunit of human chorionic gonadotropin (beta HCG), and alpha-fetoprotein were measured by means of radioimmunoassay. We studied if correlations between peripheral lymphocyte subsets and plasma hormone levels might exist. We observed in pregnant women from 10 to 40 wk of amenorrhea a decrease in the percentage of OKT3 and OKT8 cells, and during the course of pregnancy an increase in the percentage of OKT4 cells. This increase inversely correlated with plasma beta HCG levels and directly correlated with plasma HPL levels.

Immunosuppressive activity of human chorionic gonadotrophin preparations in vivo: evidence for gonadal dependence

Human chorionic gonadotrophin preparations (hCG), when injected ip daily for 4 days, suppress the delayed-type hypersensitivity (DTH) response of mice to sheep red blood cells. Preparations of crude hCG, purified hCG subunits, and hCG that was formed by recombining the purified subunits showed immunosuppressive activity in accord with their gonadotrophic activity. The immunosuppressive effects in male and female mice were comparable. However, removal of the gonads completely abrogated the immunosuppressive activity of hCG in both males and females, suggesting that the effect of hCG is mediated by a factor released from the gonads. We conclude that the hCG molecule itself exhibits immunosuppressive activity in vivo in both male and female mice and that the gonads are required for the expression of this activity.

The influence of protein hormones and conceptus extracts on sheep lymphocyte transformation induced in vitro

The study describes the effects of crude extracts of the fetal membranes of day 25 sheep conceptuses and of certain purified protein hormones and pregnancy-associated antigen on the mitogen-induced response of sheep peripheral blood lymphocytes (PBL) in vitro. A dose-dependent suppression of the proliferative response of PBL to phytohaemagglutinin, pokeweed mitogen and concanavalin-A was seen when cultures were supplemented with a soluble extract of fetal membranes. Preliminary characterization suggested that the suppressive agent was heat stable and dialysable. These properties distinguished the immunosuppressive component of membrane extracts from ovine pregnancy-associated antigen, which is heat labile and non-dialysable. However, both high and low molecular weight forms of ovine pregnancy associated antigen were also shown to inhibit lymphocyte transformation in vitro. In contrast, ovine luteinizing hormone, prolactin, growth hormone and human placental lactogen were inactive. The findings are consistent with the hypothesis that immunosuppressive substances are present in the gravid uterus during early pregnancy in the sheep.

In vitro foeto-maternal lymphocyte responses at delivery: no gross changes in MLC and PLT responsiveness

The reactivity of peripheral blood mononuclear cells of mothers and their newborns in mixed lymphocyte cultures (MLC) and primed lymphocyte typing (PLT) was tested. The primary MLC tests did not demonstrate any altered kinetics or suppression of the mother's lymphocytes towards the cells of her newborn, or vice versa. In most cases, the bidirectional MLC between maternal and newborn cells was found to be normal. Maternal lymphocytes could, however, be primed in vitro to cells from their newborn, and demonstrated a somewhat better specificity for HLA-D determinants than paternal cells similarly primed, indicating that some priming may have occurred in vivo during pregnancy.

Lack of suppression of lymphocyte MIF production by estradiol, progesterone and human chorionic gonadotropin

The hypothesis that hormones produced by the placenta contribute to immunosuppression during pregnancy is an attractive one. In order partially to evaluate this hypothesis, we utilized the Migration Inhibition Factor (MIF) Assay, which is an in vitro model of delayed hypersensitivity in that presensitized lymphocytes stimulated by antigen release a glycoprotein (MIF) which inhibits the normal migration of macrophages. The effect of placental hormones on this model of cellular immunity was tested using the direct and indirect MIF assays in pre-immunized guinea pigs. Estradiol (1-50 microgram/ml), progesterone (1-50 microgram/ml) and commercial grade or chromatography-purified hCG (1000-5000 IU/ml) did not affect normal macrophage migration and also failed to suppress production of MIF by guinea pig lymphocytes stimulated with antigen. None of the hormones either enhanced or suppressed macrophage response to preformed MIF. The results indicate that these hormones do not suppress lymphocyte reactivity as assessed by the production of lymphokines or the target cell response to the mediator. The reported effects of steroid hormones and crude hCG on other models of cellular immunity are discussed.

Immunologic regulation in pregnancy

Theories to explain the failure of rejection of the fetus by the mother during pregnancy include immunologic privilege of the uterus as a graft site, lack of transplantation antigen expression on the trophoblast, weakening of maternal cellular immunity during pregnancy, and separation of maternal and fetal circulations. Evidence for and against each of these theories is discussed. Local concentration of a variety of hormones, including human chorionic gonadotropin (HCG), sex steroids, alpha-fetoprotein, and immunoglobulins, could provide a blocking mechanism to prevent maternal cellular immune attack. Possibly, progesterone, antibodies, and immune complexes are important in protecting the placenta and ultimately the fetus from rejection. Elucidation of regulatory mechanisms in pregnancy may be applicable to other problems in immunology.

Clinical relevance of research on the structure of human chorionic gonadotropin

Human chorionic gonadotropin (hCG) has been studied extensively over the past 10 years, and some structural correlates of its chemical, biological, and immunologic properties have been defined. A review of these observations and their relevance to clinical applications of methods for detecting hCG is presented.

Experimental allergic encephalomyelitis in the guinea pig. Failure to suppress with crude human chorionic gonadotrophin

A single intraperitoneal dose of 3000 IU of crude human chorionic gonadotrophin (HCG), of proven in vitro immunosuppressive activity, gave only marginal effect on the clinical and histopathological course of experimental allergic encephalomyelitis (EAE) in guinea pigs, which did not reach statistical significance. Treatment 7 and 11 days after immunization significantly reduced the Mantoux reaction concomitant with decreased perivascular inflammation, but with unaltered or (when treated at onset) slightly enhanced clinical disease, with in vitro lymphocyte reactivity increased in accord. Much earlier treatment gave the opposite effect of a marginal improvement. HCG in vitro immunosuppressive potency was dependent on its concentration, intensity of immune response and sequence of addition. While the action of HCG on EAE does not point to an effective therapy for multiple sclerosis, as suggested by the influence of pregnancy on this disease, non-HCG fractions of urine during pregnancy may yet contain highly efficacious immunosuppressants.