Increased production of interferon gamma but not interleukin 4 in human T-lymphotropic virus type I carriers.

We investigated the production of interferon gamma (IFN-gamma), interleukin 4 (IL-4), IL-1 alpha, and tumor necrosis factor alpha (TNF-alpha) by peripheral blood mononuclear cells (PBMCs) from human T-lymphotropic virus type I(HTLV-I) carriers during short-term in vitro culture, in comparison with that by those from HTLV-I seronegative controls. PBMCs isolated from eight carriers and eight controls were cultured, and cytokine levels were measured in 1- and 3-day culture supernatants. Enhanced production of IFN-gamma was observed in all HTLV-I carriers but none of the controls. IL-4 production was not increased in the carriers except for one with a past history of toxoplasma lymphadenitis. IL-1 alpha and TNF-alpha levels were higher in the carriers. CD4+ cells were responsible for the enhanced IFN-gamma production, while monocytes were responsible for the increased IL-1 alpha and TNF-alpha production. The present study showed that the PBMCs from HTLV-I carriers consistently produced large amounts of some cytokines (IFN-gamma, IL-1 alpha, TNF-alpha) but not of other cytokines (IL-4). This imbalance in cytokine production in HTLV-I carriers may be related to the development of opportunistic infections and/or HTLV-I associated diseases including adult T-cell leukemia/lymphoma.