ABSTRACT
Human placental trophoblast is critically involved in mediating maternal tolerance of the fetal semiallograft. Genes encoding highly polymorphic major histocompatibility complex (MHC) class I and class II antigens that could provoke maternal immune rejection responses are silenced in trophoblast. However, several MHC class I or class I-related products exhibiting reduced or negligible polymorphism are expressed and assumed to be functionally involved in maintaining pregnancy. The CD1 gene family encodes non-polymorphic MHC class I-like products that have the unusual ability to present non-peptide antigens to T cells. One member, CD1D, is expressed in certain epithelial cells and interacts with a specific T-cell subset that may promote the development of Th2-mediated responses believed to be associated with pregnancy. In this study we examined the expression of CD1D in human trophoblast cell lines and placentally derived trophoblast cells by reverse transcriptase-polymerase chain reaction using CD1D-specific oligonucleotide primers. We have found that CD1D mRNA transcripts are expressed in trophoblast cells and cell lines. We have also identified a novel alternatively spliced CD1D mRNA transcript lacking exon 4. Exon 4-intact and exon 4-deficient CD1D transcripts appear to be differentially expressed in different trophoblast and non-trophoblast cell populations. Our studies suggest that at least one member of the CD1 family is transcribed in human trophoblast.
Subject(s)
Antigens, CD1/genetics , Choriocarcinoma/genetics , Neoplasm Proteins/genetics , Trophoblasts/metabolism , Uterine Neoplasms/genetics , Antigens, CD1/metabolism , Base Sequence , Choriocarcinoma/metabolism , Female , Humans , Molecular Sequence Data , Neoplasm Proteins/metabolism , Pregnancy , RNA, Messenger/genetics , RNA, Neoplasm/genetics , Reverse Transcriptase Polymerase Chain Reaction , Transcription, Genetic , Tumor Cells, Cultured , Uterine Neoplasms/metabolismABSTRACT
The expression of HLA class I Ag by term human amnion epithelial cells was investigated. In immunostaining and FACS analysis, mAb to monomorphic class I Ag reacted extensively with amnion cells, whereas polymorphic mAb reactivity was more limited and variable. Further studies were conducted on amnion cell preparations containing negligible contaminants. Northern analysis with use of locus-specific probes demonstrated that amnion expresses two class Ib genes, HLA-E and HLA-G. Radio-immunoprecipitation with use of monomorphic mAb identified two fully glycosylated cell surface class I H chains of 44 and 41 kDa; polymorphic mAbs failed to immunoprecipitate the 41-kDa product, although 44-kDa products, typical of class Ia Ag, were identified in some preparations. Class I H chains were isolated from amnion by affinity chromatography. Microsequencing revealed that the first nine residues of the N-terminus of the 41-kDa product aligned perfectly only with HLA-E. Overall, amnion at term appears to express class Ib Ag with limited class Ia Ag. HLA-G is therefore expressed in two extrafetal epithelia: amnion and trophoblast. Identification of the class Ib protein HLA-E in amnion epithelium may have implications for preterm labor that can be associated with infection of the placental membranes.
Subject(s)
Amnion/immunology , HLA Antigens/biosynthesis , HLA Antigens/genetics , Histocompatibility Antigens Class I/biosynthesis , Histocompatibility Antigens Class I/genetics , Amnion/cytology , Antibodies, Monoclonal/immunology , Base Sequence , Blotting, Northern , Cells, Cultured , Chromatography, Affinity , Female , Flow Cytometry , Gene Expression Regulation/immunology , Glycoside Hydrolases/physiology , HLA Antigens/immunology , HLA-G Antigens , Histocompatibility Antigens Class I/immunology , Humans , Immunoblotting , Molecular Sequence Data , Precipitin Tests , Trophoblasts/cytology , HLA-E AntigensABSTRACT
The (-)-enantiomer of 2'-deoxy-3'-thiacytidine (3TC) was found to be a potent and selective inhibitor of human immunodeficiency virus types 1 (HIV-1) and 2 (HIV-2) in vitro. We determined its antiviral activity against a number of laboratory strains of HIV-1 and HIV-2 in a range of CD4-bearing lymphocyte cell lines (mean 50% inhibitory concentration [IC50] range, 4 nM to 0.67 microM). 3TC was also active against a range of HIV-1 strains in peripheral blood lymphocytes (mean IC50 range, 2.5 to 90 nM). The IC50 for cytotoxicity in seven lymphocyte cell cultures, including human peripheral blood lymphocytes, ranged from 0.5 to 6 mM. 3TC had no detectable antiviral activity against a range of other viruses or in cells chronically infected with HIV-1 or HIV-2. The effects of time of addition of the compound and varying the multiplicity of infection on the antiviral activity of 3TC were determined. The results showed that 3TC is a potent and selective inhibitor of HIV-1 and HIV-2 replication in vitro.
Subject(s)
HIV-1/drug effects , HIV-2/drug effects , Zalcitabine/analogs & derivatives , Cell Death/drug effects , Cells, Cultured , Didanosine/pharmacology , Giant Cells/drug effects , HIV Reverse Transcriptase , Humans , Lamivudine , RNA-Directed DNA Polymerase/analysis , Tritium , Virus Replication/drug effects , Zalcitabine/pharmacology , Zidovudine/pharmacologyABSTRACT
Racemic 2'-deoxy-3'-thiacytidine (BCH 189) is a dideoxycytidine analog having a sulfur atom in place of the 3' carbon. The enantiomers of BCH 189 have been resolved and found to be equipotent in antiviral activity against human immunodeficiency virus types 1 and 2. However, the (-)-enantiomer (3TC) is considerably less cytotoxic than the (+)-enantiomer.
