Exaggerated Messenger RNA Expression of Inflammatory Cytokines in Human T-Cell Lymphotropic Virus Type I—Associated Myelopathy

Objective: To investigate the expression of inflammatory cytokine messenger RNA (mRNA) in peripheral blood mononuclear cells of patients with human T-cell lymphotropic virus type I (HTLV-I)—associated myelopathy (HAM). Patients: Seventeen patients with HAM, 18 HTLV-I—seropositive carriers, and 10 seronegative individuals were studied. Main Outcome Measure: We compared the expression of tumor necrosis factor α (TNF-α), granulocytemacrophage colony-stimulating factor (GM-CSF), interferon alpha (IFN-α), IFN-β, and IFN-γ, and interleukin 1α (IL-1α) and IL-1β by reverse transcriptase—polymerase chain reaction. Results: In patients with HAM, the reverse transcriptase—polymerase chain reaction products of TNF-α, GM-CSF, IFN-γ, and IL-1α were detected in significantly higher incidences than in HTLV-I—seropositive carriers and seronegative controls. Furthermore, simultaneous mRNA expression of three or more of these four cytokines was detected in all patients with HAM compared with only 21.4% of HTLV-I—seropositive carriers. By contrast, there was no significant difference in mRNA expression of IFN-α, IFN-β, and IL-1 β among patients with HAM, HTLV-I—seropositive carriers, and HTLV-I—seronegative controls. Conclusions: An exaggerated mRNA expression of several inflammatory cytokines, including TNF-α, GM-CSF, IFN-γ, and IL-1α, was demonstrated in peripheral blood mononuclear cells of patients with HAM. Moreover, transcripts of these cytokines were simultaneously up-regulated in patients with HAM, suggesting that an inflammatory state in the central nervous system may be related to the pathogenesis of HAM.