Tumors of the lung associated with HIV infection

Abstract

The human immunodeficiency virus (HIV) is a blood-borne virus that can be transmitted via sexual contact and parenteral inoculation and vertically from mother to child. Coinfection with other viruses that share similar routes of transmission (hepatitis B and C and human herpesvirus 8) is common. Two species of the human immunodeficiency virus have been identified: HIV-1 and HIV-2. Both contain three species-defining retroviral genes (gag, pol, env) and additional accessory genes that are involved in viral replication and in the disease process (Birch 2001). HIV infects CD4+ helper T cells leading to a number of qualitative and quantitative abnormalities of CD4+ lymphocytes. Progressive decline in CD4+ helper T cells resulting in decrease or inversion of the CD4/CD8 T-cell ratio and dysregulation of B-cell antibody production remains the hallmarks of HIV infection. A CD4+ T-cell count less than 200/μL is also used as a measure to diagnose acquired immunodeficiency syndrome (AIDS). The depletion of CD4+ T-cell lymphocytes is likely secondary to chronic immune activation and not due to direct cytotoxic effects of viral replication (Brenchley et al. 2006).