Inducible knockout of the interleukin-2 receptor alpha chain: expression of the high-affinity IL-2 receptor is not required for the in vitro growth of HTLV-I-transformed cell lines.
Adult T cell leukemia (ATL) is an aggressive malignancy that is associated with HTLV-I infection and characterized by constitutive expression of the high-affinity interleukin-2 receptor. The alpha subunit of the high-affinity receptor (IL-2Ralpha), which is normally present only on activated T cells, is specifically upregulated by HTLV-I and constitutively expressed on fresh leukemic cells from ATL patients as well as cell lines transformed by HTLV-I in vitro. Here we directly address the functional significance of IL-2Ralpha expression in HTLV-I transformed cell lines by using an endoplasmic reticulum-targeted single-chain antibody to inhibit the cell surface expression of IL-2Ralpha. Using constitutive and tetracycline-repressible systems to express the ER-targeted antibody against IL-2Ralpha, we have reduced cell surface expression of IL-2Ralpha by more that 2 logs of mean fluorescence intensity to virtually undetectable levels in the IL-2-independent HTLV-I-transformed cell lines C8166-45 and HUT102. No toxicity was associated with the intracellular retention of IL-2Ralpha, and the growth rate of the IL-2Ralpha-negative cells was in each case comparable to that of the parental cell line. We conclude that cell surface expression of IL-2Ralpha is dispensable for the in vitro growth of these HTLV-I-transformed cells.
Richardson
J H
JH
Division of Human Retrovirology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, Massachusetts 02115, USA.
Waldmann
T A
TA
Sodroski
J G
JG
Marasco
W A
WA
D002455:Cell Division; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D015536:Down-Regulation; D015967:Gene Expression Regulation, Viral; D015368:Human T-lymphotropic virus 1; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D013601:T-Lymphocytes / Q000473:pathology / Q000821:virology*
D007376:Interleukin-2; D015375:Receptors, Interleukin-2