Nuclear levels of NF-kappaB correlate with syncytium-forming capacity of 8e51 cells, expressing a defective HIV virus.

The double NF-kappaB site identified in the LTR of the human immunodeficiency virus-1 (HIV-1) has been demonstrated to be necessary for efficient viral transcription. In this report we present the characterisation of NF-kappaB subunits engaged in complexes binding to the HIV-1 NF-kappaB site in human 8e51 T-cells, that harbour a defective HIV-1. At least four different specific NF-kappaB complexes are present in the nucleus of these cells.

Role of HLA class I in HIV type 1-induced syncytium formation.

Neutralization of HIV-1 in vitro by anti-HLA class I antibodies suggests that class I molecules are involved in HIV-1 infection. HIV-infected cells can fuse with uninfected cells in a process that leads to the formation of multinucleated syncytia, involving an interaction between host and viral antigens expressed at the cell surfaces. We used a syncytium assay between the 8E5 cell line chronically infected with a pol-defective variant of LAV IIIb, and the CD4-positive cell line MOLT3, to study the role of HLA class I in HIV-1-induced cell fusion.

Autoantibodies to CD4 in HIV type 1-exposed seronegative individuals.

The aim of this study was to investigate the presence and the fine specificity of anti-CD4 autoantibodies in seronegative subjects sexually exposed to HIV-1. Anti-CD4 autoantibodies were previously detected in a fraction of HIV-1-seropositive individuals. Whole sera, purified IgG fractions, and supernatants of EBV-transformed lymphoblastoid cell lines were analyzed by means of ELISA, Western blot, and by competition assays using monoclonal antibodies with known fine specificities.

Human immunodeficiency virus type 1 (HIV-1)-seronegative injection drug users at risk for HIV exposure have antibodies to HLA class I antigens and T cells specific for HIV envelope.

The question of whether persistently seronegative persons at high risk for human immunodeficiency virus type 1 (HIV-1) infection exhibit HIV-1-specific T cell responses and antibodies to HIV-1 envelope epitopes shared with selected HLAs was assessed. These antibodies are not detectable by conventional serologic methods. Envelope-specific helper T (Env-Th) cell responses and antibodies specific for the HIV/HLA epitopes were studied in 21 HIV-1-negative injection drug users (IDUs).

Expression of distinct conformations of free HLA-Cw4 heavy chains in transfected neuroblastoma cells.

Epitope mapping of HLA-Cw4 indicates that the two monoclonal antibodies (mAbs) L31 and M38, specific for beta 2-microglobulin (beta2m)-free HLA-C heavy chains, react preferentially with the KYK motif, located in the binding groove (alpha1 domain). Transfection of HLA-Cw4 cDNA into a neuroblastoma cell line, which normally expresses negligible HLA class I, resulted in the constitutive surface expression of molecules displaying different reactivities with the two mAbs. This cellular system was used to determine whether L31 and M38 recognize distinct conformations of beta2m-free HLA-C proteins, and to investigate their mechanism of expression.