Isolation of a monoclonal antibody from a phage display library binding the rhesus macaque MHC class I allomorph Mamu-A1*001.

Monoclonal antibodies that bind to human leukocyte antigen (HLA) are useful tools for HLA-typing, tracking donor-recipient chimerisms after bone marrow transplants, and characterizing specific major histocompatibility complexes (MHC) on cell surfaces. Unfortunately, equivalent reagents are not available for rhesus macaques, which are commonly used animal as models in organ transplant and infectious disease research. To address this deficiency, we isolated an antibody that recognizes the common Indian rhesus macaque MHC class I molecule, Mamu-A1*001.

Interstrain gene transfer in Chlamydia trachomatis in vitro: mechanism and significance.

The high frequency of between-strain genetic recombinants of Chlamydia trachomatis among isolates obtained from human sexually transmitted infections suggests that lateral gene transfer (LGT) is an important means by which C. trachomatis generates variants that have enhanced relative fitness. A mechanism for LGT in C.

Lateral gene transfer in vitro in the intracellular pathogen Chlamydia trachomatis.

Genetic recombinants that resulted from lateral gene transfer (LGT) have been detected in sexually transmitted disease isolates of Chlamydia trachomatis, but a mechanism for LGT in C. trachomatis has not been described. We describe here a system that readily detects C.

Epitope clusters in the major outer membrane protein of Chlamydia trachomatis.

Immunopathology that is caused by re-infection with Chlamydia trachomatis is very common in humans despite regular responses to multiple, often conserved, antibody and T cell epitopes. Recurrent mutations that disrupt T cell epitopes in the major outer membrane protein in clinical isolates and the reduced transcription of HLA genes by infected cells may be evidence for pathogen evasion of protective immune responses. Subunit vaccines containing recently discovered clusters of T cell epitopes in the major outer membrane protein that are presented with diverse HLA allotypes may allow widespread protective immunization while avoiding the suppression of lasting immunity that occurs by unknown mechanisms associated with infection.

Direct detection and magnetic isolation of Chlamydia trachomatis major outer membrane protein-specific CD8+ CTLs with HLA class I tetramers.

We recently identified HLA class I-presented epitopes in the major outer membrane protein (MOMP) of Chlamydia trachomatis that elicit CTL responses in human genital tract infections. T cells possessing cytolytic activities specific for these epitopes could be detected following in vitro stimulation of peripheral blood CD8(+) T cells with peptides. In the present study we used HLA-A2 tetramers for detailed characterization of MOMP-specific CTL responses.

Definition of five new simian immunodeficiency virus cytotoxic T-lymphocyte epitopes and their restricting major histocompatibility complex class I molecules: evidence for an influence on disease progression.

Simian immunodeficiency virus (SIV) infection of the rhesus macaque is currently the best animal model for AIDS vaccine development. One limitation of this model, however, has been the small number of cytotoxic T-lymphocyte (CTL) epitopes and restricting major histocompatibility complex (MHC) class I molecules available for investigating virus-specific CTL responses. To identify new MHC class I-restricted CTL epitopes, we infected five members of a family of MHC-defined rhesus macaques intravenously with SIV.

T-cell epitopes in variable segments of Chlamydia trachomatis major outer membrane protein elicit serovar-specific immune responses in infected humans.

We previously identified 18 stimulatory Chlamydia trachomatis major outer membrane protein (MOMP) peptides containing at least 23 epitopes presented with various HLA class II allotypes. Only one peptide contained an epitope localized in a variable segment (VS2). Continued studies reported here identified a total of five VS peptides containing T-cell epitopes that are distributed among MOMPs VS1, VS2, and VS4.

T-Cell epitopes and human leukocyte antigen restriction elements of an immunodominant antigen of Blastomyces dermatitidis.

Humans infected with the dimorphic fungus Blastomyces dermatitidis develop strong T-lymphocyte responses to WI-1, an immunodominant antigen that has been shown to elicit protective immunity in mice. In the present study, the T-cell epitopes of WI-1 and human leukocyte antigen (HLA) restricting elements that display them were investigated. Peripheral blood mononuclear cells (PBMC) from 37 patients with a confirmed history of blastomycosis were tested for a response to WI-1 in primary proliferation assays; PBMC from 35 (95%) responded.

Virus-specific cytotoxic T-lymphocyte responses select for amino-acid variation in simian immunodeficiency virus Env and Nef.

Cytotoxic T-lymphocyte (CTL) responses to human immunodeficiency virus arise early after infection, but ultimately fail to prevent progression to AIDS. Human immunodeficiency virus may evade the CTL response by accumulating amino-acid replacements within CTL epitopes. We studied 10 CTL epitopes during the course of simian immunodeficiency virus disease progression in three related macaques.

Induction of HLA class I-restricted CD8+ CTLs specific for the major outer membrane protein of Chlamydia trachomatis in human genital tract infections.

HLA class I-restricted CD8+ CTLs specific for the major outer membrane protein (MOMP) of Chlamydia trachomatis are present in the peripheral blood of humans who acquired genital tract infections with the organism. Three HLA-A2-restricted epitopes and two HLA-B51-restricted epitopes were identified in serovar E-MOMP. One of the five epitopes spans a variable segment of MOMP and is likely a serovar E-specific epitope.

Characterization of the peptide binding motif of a rhesus MHC class I molecule (Mamu-A*01) that binds an immunodominant CTL epitope from simian immunodeficiency virus.

The majority of immunogenic CTL epitopes bind to MHC class I molecules with high affinity. However, peptides longer or shorter than the optimal epitope rarely bind with high affinity. Therefore, identification of optimal CTL epitopes from pathogens may ultimately be critical for inducing strong CTL responses and developing epitope-based vaccines.

Chlamydia trachomatis major outer membrane protein (MOMP) epitopes that activate HLA class II-restricted T cells from infected humans.

We localized peptide epitopes within the Chlamydia trachomatis (Ct) major outer membrane protein (MOMP) that activate human T cells. T-MOMP' cells were prepared by culturing PBL from 38 humans who had Ct infections in the presence of Ct serovar E MOMP. Some epitopes were first localized by quantifying proliferative responses of T-MOMP' cells to overlapping MOMP segments (sixths) that were produced in Escherichia coli.

The intracellular transport of MHC class II molecules in the absence of HLA-DM.

The HLA-DM alpha and HLA-DM beta genes encode a nonpolymorphic, class II-like molecule that functions by an as yet undefined mechanism in the assembly of processed antigen-HLA class II complexes. Mutant cells that fail to express HLA-DM are deficient in Ag processing. We previously isolated a subcellular compartment in mouse B cells in which functional processed Ag-class II complexes are first formed, referred to as the peptide-loading compartment.

Human placental HLA-G expression is restricted to differentiated cytotrophoblasts.

Human placental trophoblasts lie at the maternal-fetal interface, a position in which they could play an important role in maternal tolerance of the fetal semi-allograft. Central to this hypothesis is their unusual MHC class I expression: they suppress class Ia production while expressing HLA-G, a class Ib molecule. We investigated human trophoblast HLA-G protein production in vivo and in vitro.

DMA and DMB are the only genes in the class II region of the human MHC needed for class II-associated antigen processing.

Previous studies have shown that homozygous mutations between the LMP2 and DNA loci in the human MHC cause class II molecules to be abnormally conformed and unstable in the presence of SDS at low temperature, and impede class II-associated Ag processing and presentation. These abnormalities result from impaired ability to form intracellular class II/peptide complexes that predominate in normal cells. We show in this work that this defect results from deficient expression of either the DMA or the DMB gene.

Novel allele-specific, post-translational reduction in HLA class I surface expression in a mutant human B cell line.

Human B cell line .220 has a novel defect in HLA class I cell surface expression. Mutant .

Gene required for normal MHC class II expression and function is localized to approximately 45 kb of DNA in the class II region of the MHC.

In certain mutant human B cell lines, MHC-encoded class II molecules displayed at the cell surface have an abnormal conformation and are unstable in the presence of SDS. The mutants cannot present exogenous protein Ags to T cells but elicit responses with exogenous antigenic peptides; thus, formation of intracellular complexes between antigenic peptides and class II molecules is impaired. Previous analysis of LCL deletion mutants, .

Induction of anti-tumor cytotoxic T lymphocytes in normal humans using primary cultures and synthetic peptide epitopes.

Cytotoxic T lymphocytes (CTLs) recognize peptide antigens associated with cell surface major histocompatibility complex (MHC) molecules. The identification of tumor cell-derived peptides capable of eliciting anti-tumor CTL responses would enable the design of antigen-specific immunotherapies. Our strategy to identify such potentially therapeutic peptides relies on selecting high-affinity MHC binders from known tumor-associated antigens.

Presentation of cytosolic antigen by HLA-DR requires a function encoded in the class II region of the MHC.

The processing pathway for the MHC class II-restricted presentation of endogenous cytosolic Ag is distinct from the class I pathway since a cytosolic form of the influenza virus A hemagglutinin, expressed by a recombinant vaccinia virus, was presented by HLA-DR in a B cell mutant lacking the TAP1 subunit of the transporter for Ag presentation (TAP). In this report, two additional B cell mutants have been used to define the requirements of this TAP1-independent processing pathway. The first mutant, .

MHC class II deletion mutant expresses normal levels of transgene encoded class II molecules that have abnormal conformation and impaired antigen presentation ability.

Successive transfers of HLA-DR alpha and beta genes restored expression of HLA-DR antigens to human B-lymphoblastoid cell line, LCL .174, from which all known expressible class II genes are deleted. While transferent cells displayed large amounts of DR on their surfaces, transgene-encoded DR3 molecules lacked a conformation-dependent epitope.

Processing pathways for presentation of cytosolic antigen to MHC class II-restricted T cells.

Antigens presented to CD4+ T cells derive primarily from exogenous proteins that are processed into peptides capable of binding to class II major histocompatibility complex (MHC) molecules in an endocytic compartment. In contrast, antigens presented to CD8+ T cells derive mostly from proteins processed in the cytosol, and peptide loading onto class I MHC molecules in an early exocytic compartment is dependent on a transporter for antigen presentation encoded in the class II MHC region. Endogenous cytosolic antigen can also be presented by class II molecules.

No evidence for germline mutations in exons 5-9 of the p53 gene in 25 breast cancer families.

Recent studies have demonstrated that families with the Li-Fraumeni syndrome carry inherited point mutations of the p53 gene. In the present study 25 families with strong histories of breast cancer were screened for the presence of such mutations. Polymerase chain reaction products of exons 5-9 of the p53 gene were examined by single-stranded conformational polymorphism analysis and, in addition, exon 7 was further screened by direct sequencing.