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Characterization of Nef-induced CD4 T cell proliferation
B A Torres1, T Tanabe, H M Johnson
1Department of Microbiology and Cell Science, University of Florida, Gainesville 32611, USA.
Biochemical and Biophysical Research Communications
|August 5, 1996
Summary
The human immunodeficiency virus (HIV) Nef protein acts as a superantigen, activating T cells by binding to MHC class II antigens. This interaction leads to T cell proliferation and the production of key immune signaling molecules.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- The human immunodeficiency virus (HIV) regulatory protein Nef is implicated in viral pathogenesis.
- Previous research indicated Nef binds to MHC class II antigens and stimulates peripheral blood mononuclear cell (PBMC) proliferation.
Purpose of the Study:
- To further characterize the immune responses of PBMCs to the HIV Nef protein.
- To elucidate the mechanism by which Nef induces T cell activation and proliferation.
Main Methods:
- Investigated PBMC proliferation induced by Nef.
- Utilized polyclonal antisera against Nef peptides to block responses.
- Assessed T cell specificity and requirement for antigen-presenting cells (APCs).
- Examined T cell responses to inactivated APCs to determine Nef presentation form.
- Measured cytokine production (IL-2, IFN-gamma) from Nef-stimulated cells.
Main Results:
- Nef-induced PBMC proliferation was blocked by anti-Nef peptide antisera.
- Responses were T cell-dependent and required functional APCs.
- T cells proliferated even when APCs were inactivated, suggesting unprocessed Nef presentation.
- Nef-stimulated T cells produced Interleukin-2 (IL-2) and Interferon-gamma (IFN-gamma), characteristic of T helper-1 cells.
Conclusions:
- HIV Nef protein exhibits superantigen properties.
- Nef binds to MHC class II molecules and is presented in an unprocessed form by APCs.
- Nef activates T cells, leading to proliferation and T helper-1 cytokine production (IL-2, IFN-gamma).
- This finding is significant as HIV targets T cells, particularly activated T cell blasts.