Cytotoxic effect on lymphocytes of Tat from human immunodeficiency virus (HIV-1).
The human immunodeficiency virus type 1 (HIV-1) genome codes for trans-activator Tat, an 86-residue protein whose expression is critical for viral replication. Full-length Tat and Tat peptides from HIV-1 were chemically synthesized using optimized solid phase technique. Synthetic Tat2-86 was found not only to inhibit antigen-induced human peripheral blood lymphocyte (PBL) proliferation in vitro, as described by Viscidi et al. [1989, Science 246, 1606-1608], but also mitogen-induced PBL proliferation, with 50% inhibition obtained at 0.9 and 8 microM, respectively. To assess the mechanism by which Tat exert its inhibitory effect, we analysed its interaction and effect on CD4(+)-cells. Direct fluorescence and indirect immunofluorescence assays analysed by flow cytometry showed that fluorescein isothiocyanate-labeled and -unlabeled Tat interact (> 0.2 microM) with CD4-expressing lymphoid cells (CEM cell line). Experiments of chromium-51 release and Trypan blue exclusion on these tumor cells in vitro have demonstrated the capacity of Tat to modify cellular membrane permeability and cell viability, in a dose-dependent manner. The use of Tat peptides revealed that those containing the Tat basic region from 49 to 57 were able to bind to the cell membrane and to exhibit a cytotoxic activity on lymphocytes. Together, the data suggest that the potential cytotoxicity of Tat on lymphocytes could be directly implicated in virus-induced immune dysfunction observed in HIV-1 infected patients.
Benjouad
A
A
Laboratoire de Biochimie, CNRS URA 1455, Faculté de Médecine Secteur Nord, Marseille, France.
Mabrouk
K
K
Moulard
M
M
Gluckman
J C
JC
Rochat
H
H
Van Rietschoten
J
J
Sabatier
J M
JM
D000595:Amino Acid Sequence; D000941:Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D005434:Flow Cytometry; D015696:Gene Products, tat / Q000138:chemical synthesis / Q000494:pharmacology*; D015497:HIV-1 / Q000737:chemistry*; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D014373:Tuberculin / Q000276:immunology; D054322:tat Gene Products, Human Immunodeficiency Virus
D000941:Antigens; D015696:Gene Products, tat; D010446:Peptide Fragments; D010835:Phytohemagglutinins; D014373:Tuberculin; D054322:tat Gene Products, Human Immunodeficiency Virus