IMMUNOBIOLOGY Constitutive Activation of STATs Upon In Vivo Human Immunodeficiency Virus Infection

Infection by the human immunodeficiency virus (HIV) either upregulates or downregulates the expression of several cytokines and interferons (IFNs) that use the Janus kinase/ signal transducer and activator of transcription (JAK/STAT) pathway for signal transduction. However, very little is known on the state of activation of the JAK/STAT pathway after HIV infection either in vivo or in vitro. In this regard, we report here that a constitutive activation of a C-terminal truncated STAT5 (STAT5D) and of STAT1a occurs in the majority (D75%) of individuals with progressive HIV disease. We have further demonstrated that, among peripheral blood mononuclear cells (PBMCs), STAT5D is activated preferen-tially in CD41 T cells. In contrast to a published report, expression of STATs from PBMCs of infected individuals was comparable with that of seronegative donors. In addition, i