Anti-human immunodeficiency virus noncytolytic CD8+ T-cell response: a review

The CD8+ T-cell immune response for human immunodeficiency virus (HIV) is divided into a cytolytic and noncytolytic mechanism. The mechanism of cell-mediated cytotoxic immunity for the partial control of human immunodeficiency virus type 1 (HIV-1) replication in infected individuals is well-characterized, and the direct killing of virus-infected cells by antigen-specific cytotoxic T-lymphocytes (CTL) is widely correlated with disease outcome. However, the mechanism of the noncytolytic component is not well understood. In part, this is because the main inhibitory factor or factors called CD8+ T-cell antiviral factor (CAF), have not yet been purified. In addition, results between the investigators are difficult to compare because of technical differences between laboratories, including the use of different in vitro cell expansion and stimulation methods for the CD8+ T cells, the necessity of sequential biochemical purification steps with restricted amounts of material, the complex analysis and interpretation of gene expression arrays, the use of different HIV strains, and the use of different short- or long-term inhibition assays using primary or immortalized target cells. Nevertheless, the diminishing efficacy of highly active antiretroviral therapy (HAART) because of the development of resistant HIV and the persistence of latent HIV provides a strong rationale for an immune therapy approach using antiviral factor(s) of the CD8+ T-cell noncytolytic immune response.