CD8+ T-Cells: Function and Response to HIV Infection

Abstract

CD8+ T-cells are a critical component of the cellular immune response and they play an important role in the control of viral infection. During HIV infection, CD8+ T-cells are able to recognize infected cells through an MHC-I dependent process and are able to lyse cells harboring viral infection by the secretion of perforin and granzymes. These cytotoxic T-lymphocytes (CTL) can also eliminate virally infected cells through the engagement of death-inducing ligands expressed by CD8+ T-cells with death receptors on the surface of the infected cell. In addition, CD8+ CTL secrete soluble factors such as beta-chemokines and the CD8+ antiviral factor (CAF) that suppress viral binding and transcription, respectively. In order for HIV to survive the pressures placed upon it by the immune system, the virus has adopted numerous strategies to evade the CD8+ T-cell response. The high mutation rate of HIV has allowed the virus to escape CD8+ T-cell recognition in addition to its ability to down-regulate surface MHC-I expression from infected cells. Also, by altering the pattern of cytokine production and engagement of cellular receptors, HIV disrupts proper CD8+ T-cell signaling. The resultant improper T-cell receptor (TcR) stimulation creates an anergic state in these cells. By affecting the function of CD4+ T-cells and antigen presenting cells that are required for proper CD8+ T-cell maturation, HIV is able to decrease the circulating pool of effector and memory CD8+ T-cells that are able to combat viral infection. The end result is the aberration of CD8+ T-cell function.

Long-Term Control of Simian Immunodeficiency Virus (SIV) in Cynomolgus Macaques Not Associated with Efficient SIV-Specific CD8+T-Cell Responses

“…Overall, our findings suggest that other mechanisms may have contributed to the reestablishment of the control of infection in these macaques. CD8 ϩ T cells can inhibit HIV/SIV infection through noncytolytic soluble factors (47). Several reports have suggested that these mechanisms may play a major role in the CD8-mediated partial control of SIV infection during primary infection in macaques (48)(49)(50).…”

HIV Infection Affects Streptococcus mutans Levels, but Not Genotypes

“…In HIV infection, decreased CD8+ counts are associated with immune deficiency (Gulzar and Copeland, 2004), correlated with the absence of submandibular/ sublingual saliva (Mulligan et al, 2000), and the resulting opportunistic infections in the oral cavity (Fidel, 2006). A recent study demonstrated a significant correlation between CD8+ T-cell activation levels and total bacterial 16S rDNA present in stool samples of HIV+ individuals (Ellis et al, 2011).…”

Human immunodeficiency virus type 1 long-term non-progressors: the viral, genetic and immunological basis for disease non-progression

“…+ T cells and macrophages secrete these soluble factors, which then inhibit HIV-1 replication in a non-cytolytic fashion (Gulzar & Copeland, 2004).…”