Demonstration of HTLV-Related Pro viral DNA Sequences and Antibodies Reactive with HTLV Internal Proteins in an Hungarian Patient with Sézary Syndrome

DNA sequences distantly related to the proviral DNA of HTLV-I were found in the leukemic cells of a Hungarian patient suffering from Sézary syndrome. Serum samples from the patient contained antibodies reactive with the internal core polypeptides of HTLV-I and HTLV-II, but not with the env gene encoded type-specific HTLV antigens. The husband and daughter of the patient also had antibodies of the same specificity. These findings suggest the presence of a virus distantly related to HTLV-I and HTLV-II.

Frequent methylation of p16INK4A and p14ARF genes implicated in the evolution of chronic myeloid leukaemia from its chronic to accelerated phase

The frequency and mechanism of p16(INK4A) and p14(ARF) gene alterations were studied in cell samples from 30 patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia (CML), both at diagnosis and at the onset of the accelerated phase (AP) of the disease. No alterations in the p16(INK4A) or p14(ARF) genes were found in any of the chronic phase (CP) samples. DNA sequencing analyses detected p16(INK4A) or p14(ARF) mutations in 17 AP samples. All mutations were heterozygous without loss of the other allele. Aberrant methylation of the p16(INK4A) or p14(ARF) promoters was found in 14 of 30 AP samples. The most common situation was the simultaneous methylation of both promoters. Our data indicate that p16(INK4A) and p14(ARF) are primary targets for inactivation by promoter methylation in the acceleration of CML. Transcriptional silencing of the p16(INK4A) and p14(ARF) genes may be important in the conversion of CML from the CP to the AP.

Vertical transmission of human immunodeficiency virus

Sensitive detection methods, such as DNA PCR and RNA PCR suggest that vertical transmission of human immunodeficiency virus (HIV) occurs at three major time periods; in utero, around the time of birth, and postpartum as a result of breastfeeding (Fig. 1). Detection of proviral DNA in infant's blood at birth suggests that transmission occurred prior to delivery. A working definition for time of infection is that HIV detection by DNA PCR in the first 48 h of life indicates in utero transmission, while peripartum transmission is considered if DNA PCR is negative the first 48 h, but then it is positive 7 or more days later [1]. Generally, in the breastfeeding population, breast milk transmission is thought to occur if virus is not detected by PCR at 3-5 months of life but is detected thereafter within the breastfeeding period [2]. Using these definitions and guidelines, studies has suggested that in developed countries the majority, or two thirds of vertical transmission occur peripartum, and one-third in utero [3-6]. The low rate of breastfeeding transmission is due to the practice of advising known HIV-positive mothers not to feed breast milk. However, since the implementation of antiretroviral treatment in prophylaxis of HIV-positive mothers, some studies have suggested that in utero infection accounts for a larger percentage of vertical transmissions [7]. In developing countries, although the majority of infections occurs also peripartum, a significant percentage, 10-17%, is thought to be due to breastfeeding [2, 8, 9].

Induction of HIV-1 replication in latently infected syncytiotrophoblast cells by contact with placental macrophages: role of interleukin-6 and tumor necrosis factor-alpha

The syncytiotrophoblast (ST) layer of the human placenta has an important role in limiting transplacental viral spread from mother to fetus. Although certain strains of human immunodeficiency virus type 1 (HIV-1) may enter ST cells, the trophoblast does not exhibit permissiveness for HIV-1. The present study tested the possibility that placental macrophages might induce replication of HIV-1 carried in ST cells and, further, that infected ST cells would be capable of transmitting virus into neighboring macrophages. For this purpose, we investigated HIV-1 replication in ST cells grown alone or cocultured with uninfected placental macrophages. The macrophage-tropic Ba-L strain of HIV-1, capable of entering ST cells, was used throughout our studies. We demonstrated that interactions between ST cells and macrophages activated HIV-1 from latency and induced its replication in ST cells. After having become permissive for viral replication, ST cells delivered HIV-1 to the cocultured macrophages, as evidenced by detection of virus-specific antigens in these cells. The stimulatory effect of coculture on HIV-1 gene expression in ST cells was mediated by marked tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) release from macrophages, an effect caused by contact between the different placental cells. Results of this study suggest an interactive role for the ST layer and placental macrophages in the dissemination of HIV-1 among placental tissue. Data reported here may also explain why macrophage-tropic HIV-1 strains are transmitted preferentially during pregnancy.

Pseudotypes of vesicular stomatitis virus-bearing envelope antigens of certain HIV-1 strains permissively infect human syncytiotrophoblasts cultured in vitro: implications for in vivo infection of syncytiotrophoblasts by cell-free HIV-1

Intrauterine infection of the fetus is clearly an important mode of vertical transmission of human immunodeficiency virus type 1 (HIV-1). The syncytiotrophoblast layer of the human placenta must be traversed by HIV-1 in order to reach underlying cells and fetal capillaries. Although HIV-1 has been detected in the syncytiotrophoblast layer in situ, there is conflicting evidence regarding infection of syncytiotrophoblast cells with cell-free virus. The phenotypic mixing between HIV-1 and vesicular stomatitis virus (VSV) has been exploited to assay the susceptibility of human term syncytiotrophoblast cells to penetration by various strains of HIV-1. VSV(HIV-1(IIIB)) and VSV(HIV-1(Ba-L)) pseudotypes were found to enter syncytiotrophoblast cells. In contrast, VSV pseudotyped with envelope glycoproteins of RF, MN, or Ada-M strains of HIV-1 did not infect syncytiotrophoblasts. Plating efficiency of VSV(HIV-1(IIIB)) and VSV(HIV-1(Ba-L)) was 10-fold lower on syncytiotrophoblasts than on T-cells and macrophages, respectively. Incubation of VSV(HIV-1(IIIB)) and VSV(HIV-1(Ba-L)) viruses with appropriate HIV-1 neutralizing sera before infection strongly inhibited entry of pseudotyped VSV into syncytiotrophoblast cells. These findings demonstrated that infection of syncytiotrophoblasts with VSV(HIV-1) pseudotypes was mediated by Env from IIIB and Ba-L strains of HIV-1. Monoclonal antibodies (MAb) to CD4, CXCR4, CCR5, and CCR3 were tested for their ability to block VSV(HIV-1) infection of syncytiotrophoblast cells. Neither the anti-CD4 nor the anti-CXCR4, anti-CCR5, and anti-CCR3 MAb had any inhibitory effect on infection of syncytiotrophoblast cells with VSV(HIV-1) pseudotypes. Results from this study suggest that cell-free HIV-1 can enter syncytiotrophoblasts and the susceptibility of these cells to penetration by the virus is strain dependent. Pseudotype infection merely demonstrates that the first steps in HIV-1 replication are possible in syncytiotrophoblast cells.

High level of anticholesterol antibodies (ACHA) in HIV patients. Normalization of serum ACHA concentration after introduction of HAART

Anticholesterol antibodies (ACHA) are natural antibodies against the 3beta-OH group of cholesterol. Since lipid disorders are common in HIV infection and HAART may further enhance dislipidaemia, we determined by using an ELISA method serum ACHA concentrations in HIV patients and healthy HIV-seronegative controls. ACHA levels were almost 4 times higher in the sera of 46 patients than in 110 controls. No difference in the specificity of ACHA was found between HIV-seropositive and HIV-seronegative sera. Binding of ACHA to cholesterol-coated plates from a HIV-seropositive serum was dose-dependently inhibited by preincubation with HIV-1(BA-L) preparation. Serum concentration of ACHA was significantly higher in the patients with low serum cholesterol levels than in those with normal cholesterol levels. HAART induced a marked drop of ACHA concentration. We found a significant negative correlation between the length of HAART and the ACHA levels. By contrast, HAART did not significantly influence total IgG concentration and titers of antibodies against 60 kD heat shock protein. Our findings indicate that high levels of ACHA in HIV-infection may contribute to the development of hypocholesterolaemia frequently observed in this disease.

Soluble gC1q-R/p33, a cell protein that binds to the globular "heads" of C1q, effectively inhibits the growth of HIV-1 strains in cell cultures

C1q and the outer envelope protein of HIV, gp120, have several structural and functional similarities. Therefore, it is plausible to assume that proteins that are able to interact with C1q may also interact with isolated gp120 as well as the whole HIV-1 virus. Based on this hypothesis, we studied the potential ability of the recombinant form of the 33-kDa protein, which binds to the globular "heads" of C1q (gC1q-R/p33), to inhibit the growth of different HIV-1 strains in cell cultures. gC1q-R/p33 was found to effectively and dose-dependently inhibit the production of one T-lymphotropic (X4) and one macrophage-tropic (R5) strain in human T cell lines (MT-4 and H9) and human monocyte-derived macrophage cultures, respectively. At a concentration range of 5-25 microg/ml, gC1q-R caused a marked and prolonged suppression of virus production. The extent of inhibition was enhanced when gC1q-R was first incubated with and then removed from the target cell cultures before virus infection, compared to that when the cells were infected with gC1q-R-HIV mixtures. The extent of inhibition was comparable to that of the Leu3a anti-CD4 antibody. Addition of gC1q-R to the cell cultures on day 1 or 2 after infection induced markedly less inhibition of HIV-1 growth than pretreatment of the cells just before or together with the infective HIV strains. In ELISA experiments, gC1q-R did not bind to a solid-phase recombinant gp120 while strong and dose-dependent binding of gC1q-R to solid-phase CD4 was observed. Our present findings indicate that gC1q-R is an effective inhibitor of HIV-1 infection, which prevents viral entry by blocking the interaction between CD4 and gp120. Since gC1q-R is a human protein, it is most probably not antigenic in humans. It would seem logical, therefore, to consider gC1q-R or its fragments involved in the CD4 binding as potential therapeutic agents.

Alterations of P53 and RB genes and the evolution of the accelerated phase of chronic myeloid leukemia

Using the single-strand conformation polymorphism and heteroduplex analyses, the P53 and RB genes were analyzed in cell samples from twenty-eight patients with chronic myeloid leukemia (CML) both at diagnosis and at the onset of accelerated phase (AP) of the disease. No alterations of the P53 or RB genes were found in any of the chronic phase (CP) samples. Structural abnormalities of the P53 gene were observed in ten of twenty-eight AP samples within exons 4, 5, 7 and 9. Of the ten cases of AP disease with altered P53 genes, five patients also suffered from the deletion of the other allele. Alterations of the RB gene could be detected in six AP samples, and aberrant band patterns were found in the analysis of exons 2, 3, 4, 6, 7, 13, 14, 17, 21 and 26. Among the six AP samples with structural abnormalities of the RB gene, two showed the loss of the other allele. It is of note that alterations of both P53 and RB genes were observed in two AP samples. Our data strongly suggest that abnormalities of the P53 and RB genes and acceleration of CML are linked events in some cases of AP.

Differential patterns of interaction between HIV type 1 and HTLV type I in monocyte-derived macrophages cultured in vitro: implications for in vivo coinfection with HIV type 1 and HTLV type I

The interaction between human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia-lymphoma virus type I (HTLV-I) has generated substantial interest. However, there is disagreement on the in vivo consequences of the double infection. We investigated the interactions between HIV-1 and HTLV-I in monocyte-derived macrophages cultured in vitro. For study, the T cell-tropic strain IIIB and the macrophagetropic strain Ada-M of HIV-1 were used. The HTLV-I was prepared from the supernatants of the virus-producing MT-2 cell line. We found that coinfection of macrophages with T cell-tropic HIV-1 and HTLV-I significantly enhanced HIV-1 replication, whereas double infection of the cells with macrophage-tropic HIV-1 and HTLV-I resulted in marked upregulation of HTLV-I production. Stimulatory interactions between HIV-1 and HTLV-I were mediated by their trans-acting proteins. Results of study on nuclear translocation of proviral DNA showed that the tax gene product of HTLV-I was able to facilitate the nuclear import of the reverse-transcribed HIV-1(IIIB) DNA. In contrast, the HIV-1 Tat protein did not increase the intranuclear trafficking of HTLV-I DNA, which suggests another mechanism for HTLV-I enhancement by the tat gene product. In conclusion, this study provides possible mechanisms whereby coinfection of an individual with HIV-1 and HTLV-I may influence the clinical outcome of double infection.

Placental macrophage contact potentiates the complete replicative cycle of human cytomegalovirus in syncytiotrophoblast cells: role of interleukin-8 and transforming growth factor-beta1

Although syncytiotrophoblast (ST) cells can be infected by human cytomegalovirus (HCMV), in vitro studies have indicated that ST cells do not support the complete viral reproductive cycle, or HCMV replication may occur in less than 3% of ST cells. The present study tested the possibility that placental macrophages might enhance activation of HCMV carried in ST cells and, further, that infected ST cells would be capable of transmitting virus to neighboring macrophages. For this purpose, we studied HCMV replication in ST cells grown alone or cocultured with uninfected placental macrophages. Our results demonstrated that HCMV gene expression in ST cells was markedly upregulated by coculture with macrophages, resulting in release of substantial amounts of infectious virus from HCMV-infected ST cells. After having become permissive for viral replication, ST cells delivered HCMV to the cocultured macrophages, as evidenced by detection of virus-specific antigens in these cells. The stimulatory effect of coculture on HCMV gene expression in ST cells was mediated by marked interleukin-8 (IL-8) and transforming growth factor-beta1 (TGF-beta1) release from macrophages, an effect caused by contact between the different placental cells. Our findings indicate an interactive role for the ST layer and placental macrophages in the dissemination of HCMV among placental tissue. Eventually, these interactions may contribute to the transmission of HCMV from mother to the fetus.

Strong correlation between the complement-mediated antibody-dependent enhancement of HIV-1 infection and plasma viral load

OBJECTIVE

We have previously demonstrated that complement-mediated antibody-dependent enhancement (C-ADE) of HIV-1 infection correlates with accelerated immunosuppression and disease progression in HIV-1-infected individuals. In the present work the relationship between C-ADE and plasma HIV-1 RNA concentrations was studied to determine the effect of C-ADE on viral replication.

METHODS

Three studies were performed: (a) C-ADE and HIV-1 RNA concentrations were determined in the serum and plasma aliquots taken at the same time from 98 HIV patients, mostly in the advanced stage of the disease; (b) the above two parameters as well as HIV enzyme-linked immunosorbent assay (ELISA)-reactive antibodies (Abbott HIV 1/2 test), and p24 antigen levels (Abbott antigen test; Abbott, Delkenheim, Germany) were determined in four seroconversion panels purchased from the Boston Biomedica firm; (c) changes of HIV-1 RNA concentration and C-ADE during a 17 month follow-up period were determined in 18 HIV-infected patients. C-ADE was measured by the method previously established in our laboratories. The results were expressed by an enhancement/neutralization index (E/NI). HIV-1 RNA levels were determined with the Amplicor monitor kit (Roche, Basel, Switzerland), and in some experiments with the nucleic acid sequence based amplification (Organon Teknika, Turnhout, Belgium) kits.

RESULTS

(a) We found a highly significant (P<0.0001) positive correlation between E/NI values reflecting the extent of HIV-1 infection enhancement and plasma HIV-1 RNA levels. Both E/NI and HIV-1 RNA levels negatively correlated to the CD4 cell counts. (b) C-ADE was first detected just before, or concomitantly with, seroconversion in 4/4 seroconversion panels. (c) Both E/NI values and HIV-1 RNA levels significantly (P<0.001) increased during a 17 month observation period in 18 HIV-infected patients.

CONCLUSION

We found strong association between the extent of the complement-mediated antibody-dependent enhancement of HIV-1 infection and the plasma viral load in HIV patients. On the basis of these findings, C-ADE correlates with HIV replication in vivo, and potentially contributes to the progression of HIV disease.

Enzymatic hydrolysis and biological activity of oligonucleotides containing 5-substituted pyrimidine bases

Two series of alternating ODNs containing 5-n.alkyl-, alkenyl- and alkynyl-dU and -dC units have been prepared in order to study the kinetics of their hydrolysis by SV PDE and human serum, respectively. Both in (r5dUpdA)10 and (r5dCpdG)6 series the rate of hydrolysis decreased with increasing length of side-chain. Replacement of thymidines by 5-hexynyl-dU in different antisense oligomers resulted in considerably higher biological activity relative to that of the thymidine-containing counterparts.

C1q autoantibodies in HIV infection: correlation to elevated levels of autoantibodies against 60-kDa heat-shock proteins

Antibodies to solid phase C1q (C1qAb) were determined in 295 serum samples from 132 HIV-infected subjects and in sera from 140 HIV-seronegative healthy individuals as control. An ELISA method applied for the determination of C1qAb in other diseases was used. In part of these sera, other autoantibodies (antibodies reacting with 60-kDa human heat shock protein (hsp60) or mycobacterial hsp65; IgA and IgG class antibodies against the Fab and F(ab')2 moieties of IgG) as well as complement-mediated antibody-dependent enhancement/neutralization (C'-ADE) were also determined. Increased amount of C1qAb was found in HIV-infected subjects as compared with HIV-seronegative controls (P = 0.0138). In 17 of 132 (13.0%) seropositive individuals but only in 7/140 (5.0%) samples from the controls, the amount of C1qAb exceeded the upper limit (95th percentile) of the normal values (P = 0.031). The amount of C1qAb significantly decreased during a follow-up period of 65 months. C1qAb levels were found to strongly correlate to hsp60/65 autoantibodies but did not correlate or only weakly correlated to the amount of anti-Fab or anti-F(ab')2 autoantibodies measured in the same serum samples. Anti-C1q antibodies recognized the solid phase hsp60/65. Three predicted epitope regions of M. paratuberculosis hsp65 were able to bind efficiently C1q antibodies. An inverse correlation was found between C1qAb and C'-ADE, neutralization was more frequent in the sera with detectable C1qAb, whereas sera without C1qAb more likely enhanced HIV infection in vitro.

Role of interleukin-8 and transforming growth factor-beta1 in enhancement of human cytomegalovirus replication by human T cell leukemia-lymphoma virus type I in macrophages coinfected with both viruses

Human cytomegalovirus (HCMV) is one of the most frequent opportunistic agents causing severe illness in chronic human T cell leukemia-lymphoma virus type I (HTLV-I) infection. Our previous studies have shown that coinfection of macrophages with HCMV and HTLV-I significantly enhances HCMV replication, resulting in release of infectious HCMV from dually infected cells. We found that double infection of macrophages with HCMV and HTLV-I induced a rapid production of substantial amounts of interleukin-8 (IL-8) and transforming growth factor-beta1 (TGF-beta1). Results of transfection studies demonstrated that the tax gene product of HTLV-I was able to induce secretion of IL-8 and TGF-beta1. In addition to its cytokine-inducing effect, the Tax protein could interact with HCMV synergistically to result in production of much higher levels of IL-8 and TGF-beta1 than expected on the basis of their separate activities. Treatment of dually infected macrophage cultures with neutralizing antibodies to IL-8 and TGF-beta1 led to a nearly 1000-fold decrease in release of infectious HCMV from coinfected cells. Similar results were obtained when anti-IL-8 and anti-TGF-beta1 treatments were combined in macrophage cultures transfected with the tax gene before HCMV infection. Our results suggest that the stimulatory effect of HTLV-I Tax protein on HCMV replication in coinfected macrophages is largely mediated by high levels of IL-8 and TGF-beta1 production.

Changes in oncogene expression implicated in evolution of chronic granulocytic leukemia from its chronic phase to acceleration

Expression of nine oncogenes was investigated in cell samples from fifteen patients with Philadelphia chromosome (Ph)-positive chronic granulocytic leukemia (CGL) both at diagnosis and at the onset of accelerated phase (AP) of the disease. The bcr-abl fusion gene, the H-ras gene and the c-myb gene were universally expressed. In comparison with the chronic phase (CP) of the disease, an increase in the levels of bcr-abl-, c-myb- and H-ras-related transcripts was found in three, two and three AP samples, respectively. Elevation of the bcr-abl-related message was associated with duplication of the Ph chromosome and amplification of the bcr-abl fusion gene in one AP sample. No CP samples were positive for c-myc or c-sis expression. On the contrary, c-myc and c-sis were expressed in three and four AP samples, respectively. The presence of c-myc-related transcript was associated with trisomy 8 with or without amplification of the c-myc oncogene in leukemia cells of two patients with CGL in AP. No changes of oncogene expression were found in four AP samples. However, we observed deletions of chromosome 13 and 17 or i(17q) in three of them, suggesting that tumor suppressor gene alterations may also be responsible for the development of AP of CGL. Our data indicate that heterogeneous alterations in oncogenes and tumor suppressor genes accompany the evolution of CGL-CP to the AP of the disease.

Reciprocal interactions between human cytomegalovirus and human T cell leukemia-lymphoma virus type I in monocyte-derived macrophages cultured in vitro

Infection of macrophages with human cytomegalovirus (HCMV) has been shown to be nonlytic and exclusively cell associated. Human T cell leukemia-lymphoma virus type I (HTLV-I) is capable of establishing productive infection in macrophages. We studied the interactions between HCMV and HTLV-I in monocyte-derived macrophages cultured in vitro. We found that coinfection of macrophages with HCMV and HTLV-I significantly enhanced HCMV replication, resulting in release of infectious HCMV from dually infected cells. On the other hand, HCMV inhibited HTLV-I replication in macrophages coinfected with both viruses. Reciprocal interactions between HCMV and HTLV-I were mediated by their trans-acting proteins. Results of transfection studies demonstrated that the tax gene product of HTLV-I alone was capable of upregulating HCMV production. In a transient gene expression assay the immediate-early 2 (IE2) protein of HCMV alone could inhibit HTLV-I replication, whereas the IE1 protein, which had no effect by itself, produced a synergistic inhibitory effect together with the IE2 protein. Results from this study suggest that in vivo double infection of macrophages with HCMV and HTLV-I may contribute to the dissemination of HCMV infection in patients suffering from HTLV-I-associated T cell leukemia-lymphoma.

Two parallel routes of the complement-mediated antibody-dependent enhancement of HIV-1 infection

OBJECTIVE

To study the mechanism of the complement-mediated antibody-dependent enhancement (C'-ADE) of HIV infection which may play a significant role in the progression of HIV-disease.

METHODS

In vitro complement activating and complement-mediated HIV-infection enhancing abilities of three human anti-gp41 monoclonal antibodies (MAb) were tested. C'-ADE was estimated using HIV-1IIIB and CR2 (CD21)-carrying MT-4 target cells. Normal human serum (NHS), purified C1q, C1q-deficient (C1qD) and C2-deficient (C2D) human sera were applied as complement sources.

RESULTS

All MAb mediated increased C1q binding to solid-phase gp41. All MAb had a marked dose-dependent and strictly complement-mediated HIV-infection enhancing effect. Mixtures of the MAb with purified C1q also significantly increased HIV-1 infection. C1qD serum had a markedly lower enhancing effect than NHS, which could be raised to normal level by addition of purified C1q. Pretreatment of the target cells with anti-CR2 antibodies only partially inhibited the enhancing effect of the MAb plus normal human serum.

CONCLUSION

These novel findings indicate that besides the well-known facilitation of entry of HIV-1 by the interaction between virus-bound C3 fragments and CR2 present on the target cells, fixation of C1q to intact virions also results in an enhanced productive HIV-1 infection in the MT-4 cell cultures.

Epstein-Barr virus permissively infects human syncytiotrophoblasts in vitro and induces replication of human T cell leukemia-lymphoma virus type I in dually infected cells

Epstein-Barr virus (EBV) and human immunodeficiency virus type 1 (HIV-1), as well as human T-cell leukemia-lymphoma virus type I (HTLV-I), may interact in the pathogenesis of human retroviral infections. The placental syncytiotrophoblast layer represents a barrier protecting the fetal compartment from exposure to retroviruses. We studied the interactions of EBV with HIV-1 and HTLV-I in human term syncytiotrophoblast cells to investigate the significance of double infections in transplacental transmission of human retroviruses. We found that syncytiotrophoblast cells could be productively infected with EBV. Dual infection of the cells with EBV and HTLV-I resulted in full replication cycle of otherwise latent HTLV-I. In contrast, the restricted permissiveness of syncytiotrophoblasts for HIV-1 was not influenced by coinfection of the cells with EBV. Infection of syncytiotrophoblast cells with EBV, but not HTLV-I, induced interleukin-2 and interleukin-6 secretion, and augmented secretion occurred on coinfection with both viruses. Coinfection of syncytiotrophoblast cells with EBV and HTLV-I induced tumor necrosis factor-beta and transforming growth factor-beta 1 secretion, but infection with either virus alone did not lead to secretion of these cytokines. Permissive replication cycle of HTLV-I was induced by the EBV immediate-early gene product Zta. Pseudotype formation between EBV and HTLV-I in coinfected syncytiotrophoblast cells was not found. Our data suggest that activation of HTLV-I gene expression by EBV in coinfected syncytiotrophoblast cells may be a mechanism for transplacental transmission of HTLV-I.

Effects of human trophoblast-induced interferons on the expression of proto-oncogenes c-fms/CSF-1R, EGF-R and c-erbB2 in invasive and non-invasive trophoblast

The human cytotrophoblast is the first fetal cell type to arise during embryogenesis and differentiate along two pathways to the invasive (extravillous) and non-invasive (villous) populations. The non-invasive villous trophoblast differentiate morphologically and biochemically to form terminally differentiated multinucleated syncytial trophoblast. First trimester invasive and non-invasive trophoblast were isolated from human placentae (5-12 weeks) and were cultured in vitro. The villous trophoblast cells differentiated in vitro to form aggregated syncytial cells which was associated with increased expression of epidermal growth factor receptor (EGF-R). The invasive trophoblast cells expressed colony-stimulating factor receptor (c-fms/CSF-1R) and c-erbB2 proteins but low levels of EGF-R. We studied the effects of human trophoblast-induced interferon (IFN)-alpha/beta on the expression of c-fms/CSF-1R, EGF-R and c-erbB2 whose ligands are reported to be involved in the regulation of growth and differentiation of normal invasive and non-invasive trophoblast cells. Human trophoblast-induced IFN-alpha/beta (100 IU/ml) reduced the expression of EGF-R in both invasive and non-invasive trophoblast cells as determined by quantitative enzyme-linked immunosorbant assay ('ELISA') and western immunoblot methods. The same amount of IFN activity reduced the expression of c-fms/CSF-1R and c-erbB2 proto-oncogene products in invasive trophoblast cells. These results may suggest a possible role of trophoblast-induced IFNs in the regulation of normal trophoblast growth, differentiation and function.

Altered expression of the tumor suppressor/oncoprotein p53 in SV40 Tag-transformed human placental trophoblast and malignant trophoblast cell lines

The expression of the tumor suppressor/oncoprotein p53 has been investigated in normal human placental villous trophoblast, in vitro propagated invasive extravillous trophoblast, SV40 tumor antigen (Tag)-immortalized extravillous trophoblast, human cytomegalovirus (hCMV)-infected syncytiotrophoblast and malignant trophoblast (choriocarcinoma) cell lines (JAR, JEG-3 and BeWo) using quantitative enzyme-linked immunosorbent assay (ELISA) and Western immunoblot methods using monoclonal antibodies specific for wild-type and mutant p53. The normal villous and extravillous trophoblast cells expressed low levels of the wild-type p53 protein, whereas normal terminally differentiated multinucleated syncytiotrophoblast cells, as well as hCMV-infected syncytiotrophoblast, showed a higher expression of the wild-type p53 protein. SV40 Tag-immortalized invasive trophoblast cells also showed a high expression of the wild-type p53 protein which remained complexed with the Tag protein. All the choriocarcinoma cell lines over expressed the mutant form of the p53 protein. The increased expression of p53 protein in the SV40 Tag-immortalized invasive trophoblast and choriocarcinoma cells paralleled with increased expression of the mouse double minute 2 (mdm2) oncogenic protein. Transforming growth factor (TGF)-beta inhibited proliferation of normal extravillous trophoblast cells. The antiproliferative effects of TGF-beta were reduced in SV40 Tag-immortalized cells and non-detectable in choriocarcinoma cell lines JAR, BeWo and JEG-3. The inactivation of p53 owing to complexing with Tag in the immortalized premalignant trophoblast and p53 mutation in the malignant trophoblast may be responsible for their aberrant proliferation and refractoriness to antiproliferative effects of TGF-beta observed in these cells as compared to the normal trophoblast. These results may suggest the role of p53 protein in trophoblast differentiation, transformation and tumorigenesis.

Functional characteristics of human trophoblast interferons

Human trophoblast populations from first-and third-trimester placentas produce interferons (IFNs) in the presence of growth factors (CSF and PDGF) or when infected with virus. The highly invasive extravillous trophoblast population produced a higher level of IFNs (three- to eightfold, P < 0.05) than the noninvasive villous trophoblast population when stimulated with growth factors and/or virus. The level of IFN produced was dependent on the type of trophoblast population, the type of inducer and the stage of differentiation of the trophoblasts. Tandem immunoaffinity chromatography of the virus-induced trophoblast IFNs resulted in the isolation of trophoblast IFN-alpha and -beta types. The purified trophoblast IFNs have antiviral, antiproliferative and immunoregulatory properties. Furthermore, the trophoblast IFNs inhibited the expression of proto-oncogenes such as EGF-R, c-erbB2 and c-fms reported to be involved in normal trophoblast growth and differentiation. These data suggest essential roles of interferons in normal human development during pregnancy.

Bidirectional enhancing activities between human T cell leukemia-lymphoma virus type I and human cytomegalovirus in human term syncytiotrophoblast cells cultured in vitro

The syncytiotrophoblast layer of the human placenta has an important role in limiting transplacental viral spread from mother to fetus. Human cytomegalovirus (HCMV) is capable of establishing a latent infection in syncytiotrophoblast cells, with restriction of gene expression to immediate-early and early proteins. We analyzed the extent of replication of human T cell leukemia-lymphoma virus type I (HTLV-I) in human term syncytiotrophoblasts infected with HTLV-I alone or coinfected with HTLV-I and HCMV. Although syncytiotrophoblasts could be infected with cell-free HTLV-I, no viral protein expression was found in the singly infected cells. On the contrary, coinfection of the cells with HTLV-I and HCMV resulted in simultaneous replication of both viruses. Bidirectional enhancing activities between HTLV-I and HCMV were mediated primarily by the Tax and immediate-early proteins, respectively. The stimulatory effect of HTLV-I Tax on HCMV replication appeared to be mediated partly by tumor necrosis factor beta and transforming growth factor beta-1. We observed formation of pseudotypes with HTLV-I nucleocapsids within HCMV envelopes, whereas HCMV was not pseudotyped by HTLV-I envelopes in dually infected syncytiotrophoblast cells. Our data suggest that in vivo dual infection of syncytiotrophoblast cells with HTLV-I and HCMV may facilitate the transplacental transmission of both viruses.

Interactions between human immunodeficiency virus type 1 and human cytomegalovirus in human term syncytiotrophoblast cells coinfected with both viruses

Human cytomegalovirus (HCMV) and human immunodeficiency virus type 1 (HIV-1) may interact in the pathogenesis of AIDS. The placental syncytiotrophoblast layer serves as the first line of defense of the fetus against viruses. We analyzed the patterns of replication of HIV-1 and HCMV in singly an dually infected human term syncytiotrophoblast cells cultured in vitro. Syncytiotrophoblast cells exhibited restricted permissiveness for HIV-1, while HCMV replication was restricted at the level of immediate-early and early gene products in the singly infected cells. We found that the syncytiotrophoblasts as an overlapping cell population could be coinfected with HIV-1 and HCMV. HIV-1 replication was markedly upregulated by previous or simultaneous infection of the cells with HCMV, whereas prior HIV-1 infection of the cells converted HCMV infection from a nonpermissive to a permissive one. No simultaneous enhancement of HCMV and HIV-1 expression was observed in the dually infected cell cultures. Major immediate-early proteins of HCMV were necessary for enhancement of HIV-1 replication, and interleukin-6 production induced by HCMV and further increased by replicating HIV-1 synergized with these proteins to produce this effect. Permissive replication cycle of HCMV was induced by the HIV-1 tat gene product. We were unable to detect HIV-1 (HCMV) or HCMV (HIV-1) pseudotypes in supernatant fluids from dually infected cell cultures. Our results suggest that interactions between HIV-1 and HCMV in coinfected syncytiotrophoblast cells may contribute to the transplacental transmission of both viruses.

Human trophoblast interferons: production and possible roles in early pregnancy

Human villous and extravillous trophoblast populations were isolated from first- and third-trimester placentae and were stimulated with viral and non-viral inducers to produce interferons (IFNs). Polyriboinosinic/polyribocytidylic acid [poly(I:C)] induced exclusively IFN-beta in trophoblast cultures, whereas viruses induced mixtures of IFN-alpha subtypes and -beta. The level of IFN production was dependent on the trophoblast population, type of inducer and the stage of differentiation of the trophoblast. First-trimester extravillous trophoblast cultures produced greater than five-fold more IFN than third-trimester villous trophoblast on a per cell basis, whereas term syncytiotrophoblast produced twice as much IFN as term mononuclear villous trophoblast when stimulated with the same inducer. Pretreatment of trophoblast cultures with platelet-derived growth factor and granulocyte/macrophage-colony stimulating factor (GM-CSF) increased the trophoblast IFN production. Tandem high-performance affinity chromatography of the virus-induced trophoblast IFNs resulted in the isolation of trophoblast IFN-alpha and -beta with specific antiviral activities of 0.75-2.73 x 10(8) IU/ml protein. The trophoblast-induced IFNs have antiproliferative and immunosuppressive properties, and, furthermore, activated natural killer cell activity. These data may suggest the possible roles of these IFNs during embryonic development with regard to protection of the fetus against viral infection and maternal immunity.

Production of interferons in human placental trophoblast subpopulations and their possible roles in pregnancy

The human cytotrophoblasts are the first fetal cells to arise during embryogenesis and are the progenitor cells to villous (noninvasive), syncytiotrophoblast (noninvasive), "intermediate" extravillous (invasive), and "anchoring" extravillous (invasive) trophoblast subpopulations. These trophoblast subpopulations were isolated from first- and third-trimester placentae and were stimulated with Sendai virus, granulocyte-macrophage colony-stimulating factors (GM-CSF), and platelet-derived growth factor (PDGF) to produce interferons (IFNs). GM-CSF and PDGF induced very low levels of IFN in first-trimester extravillous and villous trophoblast subpopulations. Highly proliferating and invasive intermediate extravillous trophoblast cultures produced five- to eightfold more IFNs than villous trophoblast cultures and two- to fivefold more IFN than the syncytiotrophoblast cultures when stimulated with Sendai virus. Syncytiotrophoblast cultures produced higher levels of IFNs (up to twofold) than villous trophoblast cultures when stimulated with the same virus. Pretreatment of first-trimester extravillous and villous trophoblast cultures with GM-CSF and PDGF followed by infection with Sendai virus resulted in greater IFN production than when the cultures were stimulated with virus alone. The levels of IFN produced were dependent on the type of trophoblast, the type of inducer, and the stage of differentiation of the trophoblasts. The purified trophoblast IFNs have potent antiviral activities when assayed on human amniotic WISH cells, and they inhibited proliferation of normal trophoblasts and trophoblast-derived malignant cells in vitro without any toxicity. Furthermore, the trophoblast IFNs activated NK cell activity and suppressed mitogen-stimulated lymphocyte proliferation at concentrations of between 10 and 1,000 IU/ml. The possible functions of the trophoblast IFNs during pregnancy are discussed with respect to human placental and fetal protection and development.

Immunosuppressive effects of human placental trophoblast interferon-beta on lymphocytes in vitro

Human placental trophoblast cells produce predominantly interferon-beta-type (IFN-beta) when stimulated with viral inducers. The aim of the present study was to determine the in vitro antiproliferative effect of the trophoblast interferon-beta (tro-IFN-beta) on mitogen-stimulated and resting lymphocytes. The antiproliferative effect of the tro-IFN-beta was compared to human recombinant IFN-beta. All activities of tro-IFN-beta and human recombinant IFN-beta ranging between 10-1000 IU/ml showed suppression of proliferative responses on mitogen-stimulated and resting lymphocytes compared to cultures without IFN treatment. The inhibitory level of both tro-IFN-beta and recombinant IFN-beta was significantly higher on the stimulated than on the resting lymphocytes. Although there was a variation in the inhibition of lymphocyte proliferation by both IFNs with respect to time, there was no statistically significant difference in the antiproliferative effect of the IFNs on both resting and mitogen-stimulated lymphocytes. Since IFNs are produced locally by the placenta during pregnancy, our data suggest that in addition to the antiviral activity, the human tro-IFN-beta may participate in the local control of the maternal immune response during pregnancy at the fetomaternal interface.

Antibody-dependent enhancement of HIV-1 infection in human term syncytiotrophoblast cells cultured in vitro

We examined if Fc receptor-mediated antibody-dependent enhancement (FcR-ADE) or complement-mediated antibody-dependent enhancement (C'-ADE) of virus infection can contribute to increasing replication of HIV-1 in human syncytiotrophoblast (ST) cells. Here we report that both FcR-ADE and C'-ADE may result in enhanced virus release from HIV-1-infected ST cells. We show that FcR-ADE of HIV-1 infection in ST cells is mediated by FcRIII and other FcR(s) belonging to undetermined Fc classes and does not require CD4 receptors, whereas C'-ADE uses both CD4 and CR2-like receptors. FcR-ADE seems to be more efficient in enhancing HIV-1 replication than C'-ADE. While FcR-ADE leads to increased internalization of HIV-1, C'-ADE does not result in enhanced endocytosis of the virus. In addition, antibodies mediating FcR-ADE are reactive with the gp120 viral envelope antigen, whereas antibodies involved in C'-ADE react with the viral transmembrane glycoprotein gp41. Data suggest that both FcR-ADE and C'-ADE may contribute to the spread of HIV-1 from mother to the fetus.

Comparative study of antibodies that are associated with disease progression in HIV disease

Two types of antibodies which previously were found to be inversely associated with CD4+ cell counts and which may contribute to the progression of HIV disease were measured in parallel in 55 serum samples of 7 longitudinally tested HIV-infected patients (4 homosexual men, 3 haemophilic men) and in 15 serum samples from 15 patients with advanced AIDS. HIV-infection enhancing antibodies were determined in the presence of near-physiologic human complement concentration using a complement receptor type 2 (CR2) carrying HIV-target cell line. IgG and IgA class autoantibodies directed against human IgG-Fab fragments were measured in specific ELISA assays. In agreement with our previous studies obtained in HIV-seropositive haemophilic patients, significant negative correlations were found between CD4+ cell counts and IgG anti-Fab and IgA anti-Fab antibodies (Spearman correlation coefficient r = -0.587, P < 0.0001; and r = -0.269, P = 0.024, respectively). A significant positive correlation was observed between complement-dependent enhancing antibodies and IgA anti-Fab antibodies (r = 0.408, P = 0.003), whereas the correlation with IgG anti-Fab antibodies was only weak (r = 0.288, P = 0.034). Serum samples with high titres of complement-dependent enhancing antibodies had almost 3 times higher IgA anti-Fab autoantibody activity than sera with low titres (P = 0.0038). Our findings indicate that the two disease markers in HIV disease, enhancing antibodies and autoantibodies directed against the Fab moiety of IgG, are not identical. However, anti-Fab antibodies may contribute to complement-dependent HIV infection enhancement.

Neutralizing and enhancing antibodies measured in complement-restored serum samples from HIV-1-infected individuals correlate with immunosuppression and disease

OBJECTIVE

To study the association between the progression of HIV disease and HIV neutralization and enhancement measured in the presence of human complement.

DESIGN

Two studies were performed: (1) longitudinal measurement of the complement-dependent enhancing antibodies in parallel with T-cell subset determination in 55 serum samples from seven HIV-infected patients, and (2) determination of the titres of neutralizing and enhancing antibodies in stored samples of 21 HIV-asymptomatic patients obtained between 1986 and 1987 and follow-up of the patients until October 1992.

METHODS

HIV-1 [human T-lymphotropic virus (HTLV)IIIB strain, 100 median tissue culture infective dose (TCID50)] was incubated with twofold dilutions of sera in the presence of human complement (final dilution, 1:4) and added to MT-4 cells. HIV growth was monitored daily for 5 days using the reclustering inhibition and p24 immunofluorescence assays.

RESULTS

A significant negative correlation between the titres of enhancing antibodies and CD4+ cell count was found in longitudinal measurements. In the prospective studies, marked differences were observed between patients with undetectable, low, or high titres of enhancing antibodies in the clinical course of HIV disease: CD4+ cell counts and percentages decreased more rapidly in the high titre group within 3 years. After 5 years, AIDS developed in five out of six patients in the high titre group but only in five out of 15 of the low titre group (P < 0.05). A similar difference was observed between patients with and without neutralizing antibodies.

CONCLUSIONS

Measurement of HIV neutralization and enhancement in complement-containing serum samples using a complement receptor carrying target may provide data of clinical relevance. Neutralization appears to be associated with a favourable prognosis whereas high titre enhancing antibodies predict rapid progression of HIV disease.

Co-expression of c-abl and c-myb oncogenes in Philadelphia chromosome-negative, bcr-negative chronic myeloid leukaemia

Three cases of Philadelphia (Ph) chromosome-negative, bcr-negative chronic myeloid leukaemia (CML) have been investigated for oncogene expression by Northern blot and cytoplasmic RNA dot blot hybridization. Considerably high levels of expression of c-abl and c-myb were observed in all cases. In the Ph-negative cells the normal 6.0 and 7.0 kb c-abl and 3.8 kb c-myb transcripts were found. No amplification of c-abl or c-myb oncogenes was detected in the DNAs of Ph-negative CML cells. Data suggest that co-operation between the overexpressed c-abl and c-myb oncogenes is causally related to Ph-negative bcr-negative CML.

In vitro cytotoxic activity of cord blood NK cells against herpes simplex virus type-1 infected purified human term villous cytotrophoblast

Transplacental infection of the fetus with herpes simplex virus (HSV) is associated with high morbidity. The present study was undertaken to shed light on the possible participation of the fetal immune system in the elimination of HSV from placental unit. In a chromium release assay cultured term villous trophoblast cells, regardless of infection with HSV-1, were found resistant to lysis by cord blood natural killer (CBNK) cells. In contrast to this, CBNK cells exhibited a basal level of cytotoxic activity against placental fibroblasts, which was significantly increased by preceding infection of the target cells with HSV-1. Stimulation of CBNK cells with interferon-beta purified from trophoblast (tro-IFN-beta) increased the killing of both HSV-1 infected and uninfected fibroblast, while HSV-1-infected and uninfected term villous trophoblast cells remained resistant to lysis. IL-2-stimulated CBNK cells were able to lyse villous trophoblast cells at a low level, but no significant difference in the susceptibility of the HSV-1-infected and uninfected trophoblast cell was detected.

Differential replication of human immunodeficiency virus type 1 in CD8- and CD8+ subsets of natural killer cells: relationship to cytokine production pattern

CD8+ and CD8- subsets of peripheral blood natural killer (NK) cells were examined for susceptibility to infection with human immunodeficiency virus type 1 (HIV-1) and for the ability to produce various types of interferon (IFN) and tumor necrosis factor (TNF). HIV-1 was preferentially grown in CD8+ NK cells. The ability of CD8- NK cells to suppress HIV-1 replication was related to their ability to produce alpha IFN (IFN-alpha) upon viral induction. Induction with interleukin-2 resulted in IFN-gamma production in both subsets of NK cells. In the CD8+ subset, IFN-gamma and HIV-1 mutually enhanced the production of TNF alpha, leading to hyperactivation of viral replication, whereas in CD8- NK cells IFN-gamma primed HIV-induced IFN-alpha production. The dichotomous effects of IFN-gamma on HIV-1 replication were dependent on the IFN-alpha-producing ability of the cellular targets. These findings can explain the selective depletion of the CD16+ CD8+ subset that begins early in the in vivo HIV-1 infection.

Antiretroviral immune response and plasma interferon in different phases of chronic granulocytic leukemia

Forty patients with chronic granulocytic leukemia (CGL) were tested for antibodies and lymphocytes reacting with gibbon ape leukemia virus (GaLV) and baboon endogenous virus (BaEV) antigens as well as for plasma interferon levels. Antibodies reacting with envelope antigens of GaLV and BaEV were found frequently and in high titers in patients with the quiescent phase of CGL but rarely and in low titers in the accelerated and blastic phase of the disease. Results of radioimmunoprecipitation studies were in concordance with those obtained in virus neutralization experiments. Cellular and humoral cytotoxic activity of blood plasma and lymphocyte samples against autologous tumor cells showed a similar phase-specific distribution. Most of these activities could be blocked by GaLV and BaEV gp70 antigens. Elevated plasma interferon (IFN)-alpha levels were found in the quiescent and accelerated phase of CGL, whereas no significant differences could be detected between IFN levels of patients with the blastic crisis of CGL and those of the control persons. Follow up studies of four patients confirmed this stage-specific distribution of antiretroviral immune and interferon response.

Differential interferon production in human first and third trimester trophoblast cultures stimulated with viruses

Stimulation of human placental first and third trimester trophoblast and syncytiotrophoblast cultures with viruses [Newcastle Disease Virus (NDV) and Sendai virus] led to a high interferon (IFN) production. The magnitude of the production was dependent on the gestational age of the trophoblast, type of inducer and the stage of differentiation of the trophoblast. The data obtained indicated that the first trimester trophoblast cultures produced five to sixfold more IFN than the third trimester trophoblast on per cell basis whereas syncytiotrophoblast at term produced twice as much IFN than the mononuclear term trophoblast when stimulated with the viruses. NDV and Sendai virus produced different levels and composition of IFN-alpha and -beta in both first and third trimester trophoblast and syncytiotrophoblast cultures. Purification of the virus-induced trophoblast interferons (tro-IFNs) by tandem high-performance affinity chromatography resulted in specific activities between 0.7 and 2.7 x 10(8) IU/mg of protein when assayed on human amniotic WISH cells. The tro-IFN-alpha protected both human and bovine MDBK cells from virus infection whereas the tro-IFN-beta protected only the human cell lines tested. The possible roles of the tro-IFNs are discussed in light of the observed differences in trophoblast IFN response.

HTLV-I-related retroviral markers in Hungarian patients with mycosis fungoides

Cell and serum samples from 7 Hungarian patients with mycosis fungoides were examined for the presence of HTLV-I-related DNA sequences and antibodies recognizing HTLV-I antigens. DNA sequences distantly related to the proviral DNA of HTLV-I were shown by Southern blot hybridization in 3 patients. Serum samples from these patients contained antibodies reactive with the internal core polypeptides of HTLV-I and HTLV-II, but not with the env gene encoded type-specific HTLV antigens. Restriction enzyme analysis with EcoRI, PstI, BamHI and SacI revealed structural similarity of the provirus(es) integrated in the DNA of mycosis fungoides cells to HTLV-I but not to HTLV-II. Data suggest that these proviruses and HTLV-I are similar to each other along gag and pol regions.

HTLV-related markers in a Hungarian patient with adult T-cell leukemia

Monoclonal integration of DNA sequences related to, but not identical to HTLV-I provirus was detected in the peripheral blood lymphocytes of a Hungarian male suffering from ATL. The patient and his parents showed serological cross-reactivity with both HTLV-I and HTLV-II group-specific antigens. Restriction enzyme analysis with EcoRI, PstI, BamHI, HindIII and SacI revealed structural similarity of the provirus integrated in the DNA of ATL cells to HTLV-I but not to HTLV-II. Data suggest that this provirus and HTLV-I are similar to each other along gag and pol regions, but they are different in the env region.

Prevalence and specificity of lymphocytotoxic antibodies in different stages of HIV infection

Sera obtained from 27 HIV-infected persons were investigated for complement-dependent humoral cytotoxicity. Uninfected as well as HTLV-IIIB-infected H9 cells were used as cellular targets either before or after stimulation by phytohemagglutinin (PHA) or concanavalin A (Con-A). The degree of cytotoxicity was determined by 51Cr-release assay. Two different antibodies could be found in sera of HIV-infected persons, one being directed against HIV-induced cell surface component(s) and the other reacting with structure(s) present on activated T4 cells. Asymptomatic HIV-carries were found to have antibodies exerting complement-dependent cytotoxicity to HIV-infected T4 cells. These antibodies were reactive mainly after stimulation of HIV-infected target cells by Con-A. Sera of ARC and AIDS patients contained autoantibodies reactive with PHA-stimulated or HIV-infected T4 lymphocytes. These data suggest that HIV-specific antibodies represent an anti-viral immune defense, while autoantibodies may be important in destruction of the immune system in AIDS.

Isolation, purification and biochemical characterization of human placental interferons by tandem high-performance affinity chromatography

Human placental trophoblasts, fibroblasts and the trophoblast-derived malignant cell JAR are potent producers of interferons (IFNs) when stimulated with Sendai virus. The three cell lines produced different levels and compositions of IFN-alpha subtypes and IFN-beta. Anti-IFN globulins, Cibacron Blue F3GA and Concanavalin A were covalently immobilized on pressure-stable, macroporous polymeric matrices derivatized with vinyl sulphone (HEMA-BIO 1000 VS and HEMA 1000 VS). These supports were packed in biocompatible PEEK columns and were coupled with switching valves, to develop a tandem high-performance affinity chromatographic (HPAC) method for the isolation, purification and biochemical characterization of the IFNs produced in Sendai virus-stimulated human placental trophoblasts, fibroblasts and trophoblast-derived malignant cell, JAR, cultures. Silver-stained SDS-PAGE and gel densitometric analysis revealed the purity of the purified proteins to be between 94 and 98%. Specific activities of the purified IFNs ranged between 0.37-2.76 x 10(8) IU/mg of protein with cumulative recoveries between 90 and 92.2%. The purified IFN components exhibited quantitatively different antiviral activities in human and bovine cell lines. The utility of the tandem method for the purification and characterization of human type 1 IFNs produced from other cell lines are also discussed.

Characterization of Sendai virus-induced human placental trophoblast interferons

Human placental trophoblast cultures produce a mixture of interferons (IFNs) when challenged with Sendai virus. High-performance dye-ligand and immunoaffinity chromatography of a trophoblast IFN (tro-IFN) preparation enabled the isolation of three antigenically distinct IFNs, alpha I, alpha II 1 and beta, with Mrs of 16K, 22K and 24K respectively, by reducing and non-reducing SDS-PAGE. The major IFN, responsible for 75% of the total antiviral activity, was tro-IFN-beta, with the remaining activity being due to tro-IFN-alpha I and tro-IFN-alpha II 1, as determined by an antiviral neutralization test using specific anti-human IFN antibodies. The antiviral activities of the tro-IFNs were stable at pH 2.0 for 24 h and tro-IFN-alpha II 1 and -beta were shown to be glycoproteins. The three tro-IFNs showed different antiviral activities when assayed on human and bovine cell species; tro-IFN-alpha I and alpha II 1 protected both human and bovine (MDBK) cells from virus infection, whereas tro-IFN-beta showed a high degree of species specificity, protecting only the human cell types tested.

Neutralizing and complement-dependent enhancing antibodies in different stages of HIV infection

Reclustering and indirect immunofluorescence assays on MT-4 cells [carrying both CD4 and complement receptor type 2 (CR2)] were used to measure neutralizing and enhancing antibodies in sera obtained from HIV-1-infected individuals. Heat-inactivated sera were tested before and after mixing 1:1 with fresh seronegative human serum. Using heated samples, neutralizing antibodies were found in 20 out of 20 and 11 out of 19 serum samples of asymptomatic and symptomatic [AIDS, AIDS-related complex (ARC)] HIV-seropositive patients, respectively. In complement-restored samples, neutralizing activity was found in eight sera of asymptomatic patients and in none of the sera of AIDS and ARC patients; enhancing activity could be detected in four and 12 sera, respectively. A significant positive correlation was observed between the titres of neutralizing antibodies measured in the complement-restored samples and the absolute number of CD4+ lymphocytes. These findings indicate that the appearance of complement-dependent enhancing antibodies coincident with the loss of neutralizing antibodies may indicate a poor prognosis in HIV infection.

Purification and initial characterization of human placental trophoblast interferon induced by polyriboinosinic.polyribocytidylic acid

Human placental trophoblast interferon (tro-IFN), induced in trophoblast cultures by a superinduction procedure, was purified to a homogeneous product with retention of biological activity. The problems associated with isolation from serum-containing medium were overcome by a combination of Blue Sepharose affinity chromatography and reversed-phase HPLC (RP-HPLC) on Separon SGX C-18. This two-step purification procedure yielded tro-IFN with a specific activity of 3.4 x 10(7) international units/mg of protein. The overall recovery of interferon activity was 66.7%. The purified tro-IFN was shown to be a glycoprotein with an Mr of 24K on native and SDS-PAGE. Its antiviral activity was stable at pH 2.0 at 37 degrees C but was sensitive to heat at 56 degrees C for 1 h and was neutralized by antibodies to human IFN-beta.

Interferon production by cultured human trophoblasts and choriocarcinoma cell lines induced by Sendai virus

Human term-placental trophoblasts in primary culture were studied for an interferon (IFN) response when challenged with Sendai virus and compared to three choriocarcinoma cell lines, placental fibroblasts and placental macrophages. Normal trophoblasts were high producers and released both IFN-alpha and IFN-beta. In contrast, one choriocarcinoma cell line was a low producer and all malignant lines produced only IFN-beta. Circulating monocytes produce IFN-alpha but placental macrophages secreted IFN-beta and some IFN-alpha, suggesting that IFN production may be dependent on the stage of differentiation. A role for trophoblast IFNs in protection of the foetus against virus infections is proposed.

Neutralizing antibodies and serum interferon levels in the different stages of HIV infection

The sera of patients infected with HIV were investigated for neutralizing antibodies (NA) and interferons. All samples from asymptomatic HIV carriers contained NA in high titres. In the sera of patients with AIDS related complex and AIDS the antibodies were found rarely and in lower titres. An early peak of acid-labile interferon (IFN)-alpha was observed in asymptomatic HIV-infected persons, and a late peak was found in AIDS patients. The data suggest that HIV NA may have beneficial effect in the asymptomatic phase. The presence of acid-labile IFN-alpha may indicate stimulation of IFN system by HIV-infected cells.

Complement-dependent cytotoxicity of antibodies reactive with HIV-induced cell surface antigens in HIV-carrying haemophiliacs

Sera obtained from HIV-infected as well as uninfected haemophiliacs and from healthy subjects were investigated for the presence of lymphocytotoxic antibodies. Using the 51Cr-release test, HIV-infected haemophiliacs were found to produce serum antibodies exerting complement-dependent cytotoxic effect on HIV-infected T4 cells. The antibodies were reactive mainly when HIV-infected target cells were stimulated with concanavalin-A. Results of complement-dependent antibody cytotoxicity and indirect membrane immunofluorescence tests suggest that envelope antigen(s) of HIV may be the target(s) for cytotoxic antibodies.

Studies on the specificity of human antibodies reacting with GP70 and P15 antigens of baboon endogenous (BaEV) and gibbon ape leukaemia (GaLV) viruses

Antibodies reacting with gp70 and p15 antigens of baboon endogenous virus (BaEV) and gibbon ape leukaemia virus (GaLV) were detected by radioimmunoprecipitation (RIP) in blood plasma samples of patients with chronic granulocytic leukaemia, acute myeloid leukaemia and with potentially preleukaemic haematological disorders. Anti-gp70 antibodies were found more frequently than anti-p15 antibodies. Digestion of the carbohydrate part of gp70 antigens by glycosidase treatment abrogated the precipitation mediated by IgM antibodies, whereas that mediated by IgG antibodies was not markedly affected. Data suggest that antibodies detected in human plasma samples may have oncovirus specificity, but in considerable part of cases they can be of heterophil nature.

Antibodies to primate retrovirus antigens in circulating immune complexes of patients with acute myeloid leukemia

Circulating immune complexes were isolated from sera of 8 patients with acute myeloid leukemia (AML) in relapse, and 20 healthy blood donors. F(ab')2 fragments were prepared from the isolated complexes. Using a radioimmunoassay (RIA), these F(ab')2 fragments, the undigested complexes and the original sera were examined for the presence of antibodies against a panel of primate retrovirus antigens: gp70, p15 and p30 of gibbon ape leukemia virus (GaLV) and baboon endogenous virus (BaEV). F(ab')2 fragments derived from the immune complexes of all patients reacted with one or more of the antigens tested, whereas no antibody activity was found in the sera or undigested immune complexes of the same patients. By a competitive RIA, antigens related to GaLV and/or BaEV were found in the serum of 7 out of 8 patients. No markers of these retroviruses were detected in the F(ab')2 preparations, in immune complexes or in sera of any of the 20 control subjects. Our results indicate that a part of the circulating immune complexes in AML contain antigens related to primate retroviruses and specific antibodies to these antigens.

Detection by radioimmunoassay of antigens related to the P30 polypeptides of primate type C oncoviruses in peripheral leukocytes from patients with chronic myelogenous leukaemia

Leukocytes from patients with chronic myelogenous leukaemia were examined for antigens related to the p30 polypeptides of baboon endogenous virus (BaEV) and gibbon ape leukaemia virus (GaLV). Samples from patients with the quiescent phase of the disease proved to be negative or contained p30 of BaEV as the only viral antigen. In cases of blastoid crisis or acceleration, an antigen related to p30 of GaLV could be detected. In 5 of 6 patients, acceleration or blastoid crisis was preceded by expression of GaLV p30.

Cytotoxicity of lymphocytes and antibodies against autologous tumor cells in patients with myeloid leukaemias and preleukaemic disorders. III. Stage-dependence of oncovirus-specific immune response

Lymphocyte and plasma samples from the quiescent and blastic phase of chronic granulocytic leukaemia (CGL) and from the blastosis and remission of acute myeloid leukaemia (AML), were compared for cytotoxic activity. Target cells were collected from the blastic phases of diseases. 51Cr-release tests showed that the lymphocytes and plasma samples from blastic crisis of CGL had no cytotoxic activity for autologous blast cells. In contrast, cryopreserved lymphocytes and plasmas from the quiescent phase of CGL proved to be cytotoxic for the autologous tumor cells, and their effect could be blocked by native gp70 antigens of gibbon ape leukaemia virus (GaLV) and baboon endogenous virus (BaEV). A blocking effect was less frequently exerted by carbohydrate-free gp70 and p15(E) antigens. A similar relationship was found between the blastosis and remission stage of AML, however, out of the antigens of BaEV only the native gp70 showed a marked blocking effect.