Evidence for aberrant activation of the interleukin-2 autocrine loop by HTLV-1-encoded p40x and T3/Ti complex triggering.

In this study we provide evidence that distinct DNA sequences within the 5'-flanking regions of the genes for interleukin-2 (IL-2) and its receptor (IL-2R) are involved in human T-cell-specific activation of transcription by p40x, a product of human T cell leukemia virus type I (HTLV-1). The same DNA sequences appear to be responsible for induction of the genes in a T cell line, Jurkat, by mitogens. Although the IL-2 gene sequences are activated by p40x with much lower efficiency than the IL-2R gene sequences, they are synergistically activated by the p40x expression and subsequent extracellular stimulation by Concanavalin-A or anti-T3. We propose a model for two-step activation of the IL-2 autocrine loop in ATL development.