Human T-cell lymphotropic virus I (HTLV-I) Tax has been shown to transactivate several cellular genes. In this study, we show that interleukin 8 (IL-8) is expressed and secreted in tax-transfected Jurkat cells that were further augmented by mitogen stimulation. Expression of high-affinity IL-8-R (Type A) mRNA in these cells suggests an autocrine role for this chemokine in HTLV-I-infected T cells. However, interleukin-16 (IL-16) mRNA expression or protein secretion was not significantly modulated either constitutively or even upon mitogen stimulation in these tax-transfected cells.