title: Phenotypic and functional characterization of HTLV positive neoplastic T cells cultured with interleukin-2--II. Inhibition of lymphoproliferative responses.
abstract: T cells from the peripheral blood of a T-cell chronic lymphocytic leukemia (T-CLL) patients, were expanded by culture in the presence of interleukin-2 (IL-2). In contrast to the original leukemic T cells that showed a complete lack of suppressor activity, the proliferating T-CLL cells were extremely potent inhibitors of mitogen, antigen and alloantigen induced lymphoproliferative responses. Compared to the fresh T-CLL cells, the proliferating T-CLL cells showed an enhanced expression of the human T-cell leukemia/lymphoma virus (HTLV) p19 antigen and released type C virus particles into their culture supernatant. A direct involvement of the virus particles in the suppression was however unlikely, since the inhibition was found to be mediated by a soluble inhibitor in the culture supernatant of proliferating T-CLL cells. This inhibitor was very hydrophobic and was inactivated by treatment with trypsin, by heating to 56 degrees C for 2 h and by storage at -70 degrees C for more than 14 weeks. It could be excluded that the suppression of lymphoproliferation was due to competition for IL-2, to toxic effects, to nutrient depletion or to a shift in the kinetics of the target cell responses. Furthermore, it could not be attributed to suppressor inducer activity of the OKT4+ proliferating T-CLL cells, since normal T cells enriched for OKT4+ T cells and depleted for OKT8+ T cells were also inhibited in their proliferation. Since other hemopoietic cell lines, not of OKT4+ T lymphocyte origin, also were suppressed to proliferate, it is concluded that the proliferating T-CLL cells represent a neoplastic T-cell clone that had differentiated into suppressor effector T cells after prolonged culture in the presence of IL-2.
mesh_terms: D002453:Cell Cycle; D002478:Cells, Cultured; D017977:Deltaretrovirus / Q000302:isolation & purification*; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D007945:Leukemia, Lymphoid / Q000097:blood; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D007376:Interleukin-2; D014357:Trypsin