Downregulation of major histocompatibility class I on human dendritic cells by HIV Nef impairs antigen presentation to HIV-specific CD8+ T lymphocytes.

The HIV early regulatory Nef protein downregulates surface expression of major histocompatibility class I (MHC I) molecules on various immortalized cell lines and on T lymphocytes. MHC I-restricted presentation induces CD8+ T cell responses, which have a major role in limiting HIV infection. Induction of primary immune responses requires dendritic cells, which are major candidates as the first cells that can internalize the virus and present it to T cells in mucosal contamination.

Expression of pro-EPIL peptides encoded by the insulin-like 4 (INSL4) gene in chromosomally abnormal pregnancies.

The recent development of a specific immunoassay based on monoclonal antibodies directed to chain C and chain A of early placenta insulin-like peptide (EPIL) encoded by the INSL4 gene, has made it possible to demonstrate pro-EPIL peptide expression during normal pregnancy. In the present study, we report on the expression of pro-EPIL peptides in chromosomally abnormal pregnancies, namely trisomy 21 and 18. EPIL peptide levels were measured in amniotic fluid (AF) and maternal serum (MS) from pregnancies with trisomy 21 (n=16) or 18 (n=14) and compared to levels detected in AF and MS from 33 chromosomally normal pregnancies between 12 and 32 weeks of gestation.

Dendritic cells transfected with the nef genes of HIV-1 primary isolates specifically activate cytotoxic T lymphocytes from seropositive subjects.

The HIV-1 Nef protein down-modulates surface expression of MHC class I proteins. Primary infected T lymphocytes thus escape lysis by cytotoxic T lymphocytes (CTL). In contrast, during HIV-1 infection there are strong CTL responses to several HIV proteins, and there is mounting evidence that CTL are critical for controlling the virus.

Generation of Melan-A/MART-1-specific CD8+ cytotoxic T lymphocytes from human naive precursors: helper effect requirement for efficient primary cytotoxic T lymphocyte induction in vitro.

This study investigates the generation of primary melanoma cell-specific cytotoxic T lymphocytes (CTLs) in vitro. Induction of peptide-specific CTLs from unfractionated naive peripheral blood mononuclear cells from HLA-A2 healthy donors was assessed using 2 recently described 9-mer epitopes from the melanoma tumor antigen Melan-A/MART-1. The need for help from CD4+ T lymphocytes for the long-lasting induction of CTLs and the capacity of the peptide-induced CTL lines to recognize many melanoma cells were evaluated.

Preferential usage of the T-cell receptor by influenza virus hemagglutinin-specific human CD4+ T lymphocytes: in vitro life span of clonotypic T cells.

Human helper T-cell (Th) responses to influenza A virus were studied by analyzing T-cell receptor V beta gene diversity in hemagglutinin-specific Th lymphocytes. The T-lymphocyte population from peripheral blood became quickly oligoclonal when stimulated in vitro with the HA306-329 peptide, and T-cell receptor V beta 3 genes were mainly expanded. Moreover, specific junctional region oligonucleotide probes corresponding to hemagglutinin-specific clones were used to estimate temporal diversity during antigenic stimulations.