High levels of soluble interleukin 2 receptors released from human retrovirus-infected cells.

Soluble interleukin 2 receptors (IL 2R) from human retrovirus-infected cells were analyzed. All the T cell lines integrated with human T cell lymphotropic virus (HTLV)-I and -II, or transfected with HTLV-I gag-pX gene, were found to release high levels of IL 2R constitutively. In contrast, this was not found in T cell lines in which HTLV-I was integrated but not expressed, human immunodeficiency virus (HIV)-infected T cell lines, or T cell, B cell, granulocyte and macrophage cell lines which were HTLV-I negative. These results raise the possibility that the pX-gene product might stimulate the generation of soluble IL 2R. In the sera from patients with adult T cell leukemia, large amounts of IL 2R were released, in contrast to sera from healthy carriers of HTLV-I. The molecular weight of IL 2R was determined to be about 50 KD by size-exclusion HPLC.