Transformation of hamster spleen lymphocytes by human T‐cell leukemia virus type I

Abstract
Co‐cultivation of spleen cells of Syrian golden hamsters with lethally irradiated MT‐2 cells harboring human T‐cell leukemia virus type I (HTLV‐I) resulted in the establishment of lymphoid cell lines, HCT‐1 and HCT‐2, which exhibited the normal karyotype of golden hamsters. Cells of both the HCT‐1 and HCT‐2 lines lacked surface immunoglobulins and reacted with a monoclonal antibody (MAb) specific for hamster T cells. Some were positive for OKIal. None of them expressed HTLV structural antigens (p19 and p24) or virus particles, but they contained HTLV‐1 proviral DNA monoclonally. By immunochemical analysis of the labelled cell antigens, sera from adult T‐cell leukemia (ATL) patients reacted with the two polypeptides, p37 and p40, which may not be viral structural proteins and still remain to be characterized. HCT‐1 and HCT‐2 cells were transplantable into newborn hamsters, pre‐treated with anti‐hamster thymocyte serum and non‐treated, respectively, producing diffuse malignant lymphoma. These findings indicated that HTLV‐1 not only immortalized but also transformed hamster T cells non‐productively.