TH1 to TH2 Shift of Cytokines in Peripheral Blood of HIV-Infected Patients Is Detectable by Reverse Transcriptase Polymerase Chain Reaction but Not by Enzyme-Linked Immunosorbent Assay Under Nonstimulated Conditions

Abstract

Background: Dysregulation of cytokines has been implicated in the pathogenesis of HIV infection. Therefore, we determined tumor necrosis factor-a (TNF-α), interleukin-lβ (IL-1β), IL-4, IL-10, and interferon-γ (IFN-γ) mRNA and serum levels in HIV-infected patients under nonstimulated conditions. Material and Methods: Blood samples of 32 HIV-infected patients and 10 healthy HIV-negative controls were analyzed. Cytokine serum levels were quantified by enzyme-linked immunosorbent assay (ELISA). Cytokine mRNA levels were determined semiquantitatively by competitive reverse transcriptase polymerase chain reaction (RT-PCR) and expressed as ratios relative to those of β-actin. Results: Competitive RT-PCR was shown to be more sensitive than protein ELISA in analyzing cytokine production. We found a significant correlation between steady-state mRNA ratios and serum protein levels for TNF-α. Significantly higher cytokine mRNA ratios were found in those patients with IL-10 and IFN-γ levels detectable by ELISA. Steady-state mRNA ratios of TNF-α, IL-4, and IL-10 were significantly increased in patients with highly replicative HIV-infection. Furthermore, elevated IL-4:IFN-γ ratios were related to both high viral load and loss of CD4 cells. Discussion: Determination of steady-state mRNA ratios by semiquantitative RT-PCR represents a sensitive method to analyze cytokines in peripheral blood of HIVinfected patients under nonstimulated conditions. The data obtained with this technique provide further evidence for a TH1 to TH2 cytokine shift with progressive HIV disease.