Interferon-gamma and interleukin-4 responses in relation to serum IgE levels in persons infected with human T lymphotropic virus type I and Strongyloides stercoralis

Possible immunologic interaction between infection with human T lymphotropi c virus type 1 (HTLV-1), a retrovirus, and the intestinal parasite Strongyl oides stercoralis was investigated in persons infected with one or both age nts. This was done by examining the cytokine responses of peripheral blood mononuclear cells (PBMC) to mitogens and Strongyloides antigen, PBMC of sub jects infected with HTLV-1 spontaneously produced interferon (IFN)-gamma wi th levels that correlated inversely with serum IgE levels. HTLV-1-infected subjects also had poor interleukin (IL)-4 responses to mitogenic stimulatio n, unlike persons without HTLV-1 infection. It is postulated that the IFN-g amma produced by activated T cells in some HTLV-l-infected persons acts to down-regulate IL-4 with consequent reduction of serum IgE levels, The impai red IgE responses and other effects of IL-4 down-regulation may be contribu ting factors to more severe disease and impaired response to treatment of s trongyloidiasis in some HTLV-1-infected persons.