Human immunodeficiency virus (HIV) infection is associated with a complex pattern of alterations that profoundly affect the immune response. HIV-induced immune dysregulation will impair both the quantitative and qualitative homeostasis of the immune system and this impairment will be manifested as an array of multiple, characteristic defects. HIV infection ultimately results in the appearance of the acquired immunodeficiency syndrome (AIDS); the diagnosis of AIDS was, until the introduction of highly active antiretroviral therapy (HAART), shortly thereafter followed by death.

ProgressionofHIV-infectedpatients to AIDSresults fromdifferent factors including the intense and persistent replication of HIV, the continuous and abnormal stimulation of the immune response, and the quantitative and qualitative impairment of the immune system. We will briefly summarize these defects as well as the effects of HAART on immune reconstitution, and will present data supporting the hypothesis that an abnormally high percentage of CD8+/CD38+ T lymphocytes might be associated with lack of therapeutic success in HAART-treated patients.