Evidence for the interleukin-2 dependent expansion of leukemic cells in adult T cell leukemia

Interleukin 2 (IL-2) receptor/Tac antigen is abnormally expressed on cells of patients with adult T cell leukemia (ATL) caused by infection with human T lymphotropic virus type I (HTLV-I). Twenty-five patients with ATL were examined to determine whether their leukemic cells continued to show IL-2-dependent proliferation. In 21 patients, the in vitro proliferation of HTLV-I-infected nonleukemic T cell clones was found to be dependent on IL-2. However, clonality analysis based on T cell receptor gene rearrangement profiles and the site of HTLV-I provirus integration revealed IL-2-dependent growth in leukemic cells in four patients with ATL. These results provide evidence for the IL-2-dependent proliferation of leukemic cells in some ATL patients.

Heterogeneity in response to interleukin 2 and interleukin 2-producing ability of adult T cell leukemic cells

To examine the possibility of heterogeneous mechanisms in the proliferation of adult T cell leukemia (ATL) cells, leukemic cells from 13 patients, nine acute-type and four chronic-type ATL, were examined for the production of interleukin 2 (IL 2) with or without mitogenic stimulation and their response to recombinant IL 2 when exogeneously added. The leukemic cells were classified into four groups, as follows. Group 1 (two patients): Cells of this group produced IL 2 messenger RNA, secreted IL 2, and proliferated when cultured in mitogen-free medium. The spontaneous proliferation of the cells in mitogen-free medium was inhibited by anti-Tac/IL 2 receptor and anti-IL 2 monoclonal antibodies. Moreover, the thymidine incorporation by the cells was enhanced in response to exogeneously added recombinant IL 2 and IL 2 produced by themselves. These results indicate that the ATL cells of this group proliferate with autostimulation by IL 2. Group 2 (seven patients): Cells of this group did not secrete IL 2 when cultured in mitogen-free medium, but the cells showed response to exogeneously added recombinant IL 2 and proliferated in culture. These results indicate that the ATL cells of this group proliferate by a paracrine mechanism. Group 3 (one patient): Cells of this group secreted IL 2 in mitogen-free medium. However, the spontaneous proliferation of these cells in vitro was very low, and the response to recombinant IL 2 was also very low. Group 4 (three patients): Cells of this group did not secrete IL 2 in mitogen-free medium. Spontaneous proliferation and the response to recombinant IL 2 were also very low. The clinical feature of all patients of Groups 1 and 2 was acute-type, and that of Groups 3 and 4 was chronic-type. Thus, we conclude that heterogeneous mechanisms exist in the proliferation of leukemic cells, and that growth rate in mitogen-free medium and response to IL 2 of the cells may have a significant relationship to the clinical feature, acute- or chronic-type.

Heterogeneity in response to interleukin 2 and interleukin 2-producing ability of adult T cell leukemic cells

To examine the possibility of heterogeneous mechanisms in the proliferation of adult T cell leukemia (ATL) cells, leukemic cells from 13 patients, nine acute-type and four chronic-type ATL, were examined for the production of interleukin 2 (IL 2) with or without mitogenic stimulation and their response to recombinant IL 2 when exogeneously added. The leukemic cells were classified into four groups, as follows. Group 1 (two patients): Cells of this group produced IL 2 messenger RNA, secreted IL 2, and proliferated when cultured in mitogen-free medium. The spontaneous proliferation of the cells in mitogen-free medium was inhibited by anti-Tac/IL 2 receptor and anti-IL 2 monoclonal antibodies. Moreover, the thymidine incorporation by the cells was enhanced in response to exogeneously added recombinant IL 2 and IL 2 produced by themselves. These results indicate that the ATL cells of this group proliferate with autostimulation by IL 2. Group 2 (seven patients): Cells of this group did not secrete IL 2 when cultured in mitogen-free medium, but the cells showed response to exogeneously added recombinant IL 2 and proliferated in culture. These results indicate that the ATL cells of this group proliferate by a paracrine mechanism. Group 3 (one patient): Cells of this group secreted IL 2 in mitogen-free medium. However, the spontaneous proliferation of these cells in vitro was very low, and the response to recombinant IL 2 was also very low. Group 4 (three patients): Cells of this group did not secrete IL 2 in mitogen-free medium. Spontaneous proliferation and the response to recombinant IL 2 were also very low. The clinical feature of all patients of Groups 1 and 2 was acute-type, and that of Groups 3 and 4 was chronic-type. Thus, we conclude that heterogeneous mechanisms exist in the proliferation of leukemic cells, and that growth rate in mitogen-free medium and response to IL 2 of the cells may have a significant relationship to the clinical feature, acute- or chronic-type.

Autocrine growth of interleukin 2-producing leukemic cells in a patient with adult T cell leukemia

Leukemic cells in the peripheral blood of a patient with adult T cell leukemia (ATL), which expressed the Tac antigen/interleukin 2 (IL2) receptor, were investigated in vitro for autocrine growth by IL 2. The cells showed spontaneous proliferation in mitogen-free medium. The spontaneous proliferation of the cells was inhibited by monoclonal anti-IL 2 or anti-Tac antibody. These cells were found to produce messenger RNA for IL 2 and secrete IL 2 during short-term culture in the same medium. Recombinant IL 2 and IL 2 secreted by the cells enhanced the proliferation of the cells in a dose-dependent manner when added to the initial culture. These findings demonstrate that an autocrine mechanism by IL 2 is involved in the proliferation of ATL cells during short-term culture.

Interleukin 2 acts directly on a Tac-positive cloned B cell line established from a patient with adult T cell leukemia

A Tac-positive B cell line termed K3B was established from a patient with adult T cell leukemia (ATL). This cell line had EBNA antigen and human T cell leukemic virus (HTLV) provirus besides B1 antigen and surface immunoglobulin. A cloned Tac-positive B cell line termed K3B01 was obtained from K3B by the limiting dilution method. The K3B01 cells were shown to absorb IL 2 activity in a tonsillar IL 2 preparation. By using this cloned cell line and a purified recombinant IL 2 preparation, it was shown that the proliferation of K3B01 cells was enhanced by the addition of recombinant IL 2. Moreover, this response was inhibited by anti-Tac antibody. These results demonstrate definitively that IL 2 acts directly on B cells through IL 2 receptors on them.

Interleukin 2 acts directly on a Tac-positive cloned B cell line established from a patient with adult T cell leukemia

A Tac-positive B cell line termed K3B was established from a patient with adult T cell leukemia (ATL). This cell line had EBNA antigen and human T cell leukemic virus (HTLV) provirus besides B1 antigen and surface immunoglobulin. A cloned Tac-positive B cell line termed K3B01 was obtained from K3B by the limiting dilution method. The K3B01 cells were shown to absorb IL 2 activity in a tonsillar IL 2 preparation. By using this cloned cell line and a purified recombinant IL 2 preparation, it was shown that the proliferation of K3B01 cells was enhanced by the addition of recombinant IL 2. Moreover, this response was inhibited by anti-Tac antibody. These results demonstrate definitively that IL 2 acts directly on B cells through IL 2 receptors on them.

Human helper T cell factor(s) (ThF). II. Induction of IgG production in B lymphoblastoid cell lines and identification of T cell-replacing factor- (TRF) like factor(s)

IgG-PFC was induced in Epstein-Barr virus-transformed B lymphoblastoid cell lines (LCL) by the addition of allogeneic T cells. T cells involved in the induction of IgG-PFC were shown to belong to the Leu 3a+/2a- T cell subset. Furthermore, partially purified soluble factors obtained from the culture supernatant of PPD-stimulated pleural T cells or PWM-stimulated tonsillar mononuclear cells was shown to induce IgG-PFC in LCL across the major histocompatibility complex barrier. The induction of IgG-PFC was observed only in surface IgG-positive LCL cell populations and was not accompanied by the increase in the number of LCL cells. The factors with such a TRF-like activity were found in two fractions corresponding to the m.w. range of 18,000 to 25,000 (22K fraction) and 28,000 to 38,000 (36K fraction) by gel filtration. Isoelectric focusing of these fractions revealed that TRF-like activity of both 22K and 36K fractions distributed in the pI range of 5.0 to 6.0, and both fractions were found to be devoid of TCGF activity. These results appear to indicate that the factors act on the B cells in terminal stages to trigger final differentiation to Ig-producing cells.

Human helper T cell factor(s) (ThF). II. Induction of IgG production in B lymphoblastoid cell lines and identification of T cell-replacing factor- (TRF) like factor(s)

IgG-PFC was induced in Epstein-Barr virus-transformed B lymphoblastoid cell lines (LCL) by the addition of allogeneic T cells. T cells involved in the induction of IgG-PFC were shown to belong to the Leu 3a+/2a- T cell subset. Furthermore, partially purified soluble factors obtained from the culture supernatant of PPD-stimulated pleural T cells or PWM-stimulated tonsillar mononuclear cells was shown to induce IgG-PFC in LCL across the major histocompatibility complex barrier. The induction of IgG-PFC was observed only in surface IgG-positive LCL cell populations and was not accompanied by the increase in the number of LCL cells. The factors with such a TRF-like activity were found in two fractions corresponding to the m.w. range of 18,000 to 25,000 (22K fraction) and 28,000 to 38,000 (36K fraction) by gel filtration. Isoelectric focusing of these fractions revealed that TRF-like activity of both 22K and 36K fractions distributed in the pI range of 5.0 to 6.0, and both fractions were found to be devoid of TCGF activity. These results appear to indicate that the factors act on the B cells in terminal stages to trigger final differentiation to Ig-producing cells.

Thyrotrophin-binding inhibitory immunoglobulins and HLA-DRW3-two prognostic factors in Graves' disease

Thyrotrophin-binding inhibitory immuno-globulin (TBII) activity and HLA typing were performed in 38 Chinese patients with Graves' disease to find out the relationship among TBII activity, HLA antigen and relapse. Twelve out of 13 patients who were TBII-positive at anti-thyroid drug withdrawal relapsed. All seven patients with HLA-DR3 antigen relapsed, whereas all ten patients in remission did not have DR3. Therefore, both TBII activity at drug withdrawal and DR3 antigen could predict subsequent relapse. However, a larger patient sample is required to determine the precise relationship between TBII activity and HLA-DR3 antigen.

Relations between the HLA-antigens and immune responsiveness to SK/SD in healthy Japanese subjects

A possible association between the HLA antigens and immune responsiveness to SK/SD was studied in 90 healthy Japanese volunteers. No association was found between the HLA antigens, including B5, and SK/SD stimulated blastoid transformation. There was a week indication of an association between Bw22 and responses to SK/SD. But this was not statistically significant as far as the corrected P value was concerned.