Transient induction of IL-2 receptor in cultured T cell lines by HTLV-1 LTR-linked tax-1 gene

Abstract

Human lymphotropic virus, HTLV-1, encodes in its proviral genome a transcriptional activator protein, tax-1, that may be responsible for the development of virus-induced adult T cell leukemia (ATL), possibly through the aberrant activation of the genes for interleukin-2 (IL-2) and one of its receptor (IL-2) components, the IL-2 receptor α-chain (IL-2Rα). In the present study, an expression plasmid containing tax-1 cDNA under the control of HTLV-1 LTR was introduced into mouse and human CD4-positive T cell lines. Analysis of the established cell clones revealed a number of interesting features: (i) a limited faction of the total cell population (<25% in each clone) was positive for IL-2Rα; (ii) the IL-2Rα expression was not permanent, as the IL-2Rα positive and negative cells could convert either way. The experimental data suggest that the observed heterogeneity in IL-2Rα expression in the transformants is due to a cell-cycle-regulated expression and function of tax-1. Furthermore, a proportion of the induced IL-2R in EL-4 was in high-affinity form, suggesting the association of the IL-2Rα and the IL-2Rβ chain (p70-75) components.