Ken-Ichi Naruo

Translation of interleukin 2 mRNA from human peripheral blood leukocytes in Xenopus oocytes

Abstract Interleukin 2 was induced in cultures of human peripheral blood leukocytes by combined treatment with 12-O-tetradecanoylphorbol-13-acetate and a T-cell mitogen, Concanavalin A. Poly(A)-containing mRNA was isolated from these cultures and fractionated by sucrose density gradient centrifugation. When injected into Xenopus laevis oocytes, the mRNA preparation gave rise to interleukin 2 activity in the culture supernatant of the oocytes. The sucrose density gradient centrifugation analysis showed that the interleukin 2 mRNA sedimented at 10–12S, which suggests that it contains about 900–1,100 nucleotides.

Stimulation of Thrombopoiesis in Mice by Fibroblast Growth Factor 9

Fibroblast growth factor 9 (FGF-9), a novel member of the FGF family, was found to have thrombopoietic activity in vitro and in vivo. In an in vitro megakaryocyte colony-stimulating factor assay, anti-mouse interleukin-6 (IL-6) monoclonal antibody neutralized FGF-9 activity. This suggests that the activity may be exerted via IL-6 induction. BALB/c mice that received subcutaneous FGF-9 injections of 4 to 100 micrograms/day for 2 weeks showed a dose-dependent transient increase in peripheral platelet counts 10 to 12 days after the first treatment. Histologic studies showed a marked increase in megakaryocytes in bone marrow and extramedullary hematopoiesis in the spleen and the liver. Examination of changes in the DNA content of bone marrow megakaryocytes revealed that the ploidy distribution underwent a marked shift 3 days after FGF-9 injection, with a large increase in the 2N megakaryocyte population. The major modal ploidy shifted from the normal 16N to 2N. The number of megakaryocyte progenitor cells in FGF-9-treated mice increased up to 1.5-fold in the bone marrow and 10-fold in the spleen on day 6. These results indicate that FGF-9 acts on the in vivo proliferation of megakaryocytes.

Production of cytotoxic factor(s) in human T cell lines transformed by a human retrovirus

Human T cell lines, MT-2, TCL-Ter, TCL-Haz, and TCL-Kan which were transformed by a human retrovirus, constitutively produced cytotoxic factor(s) (CF) in the culture supernatants. In these cell lines, MT-2 produced the largest amount of CF. The amount of CF produced by MT-2 was 9-10 or 3-4 times larger than that produced by a human B cell line, RPMI 1788, or normal peripheral blood leukocytes stimulated with mitogens and phorbol ester. The kinetics of the production by MT-2 was similar in media with and without serum. The activity was stable at 56 degrees C for 30 min but was lost at 80 degrees C for 30 min and at pH 2 for 20 hr. On gel filtration, the molecular weight of the factor produced by MT-2 was approximately 90,000. On isoelectric focusing, the activity was recovered in the fraction at pH 6.5-7.0.

Characteristics of mouse lymphoid cells proliferating in vitro by recombinant human interleukin 2 (TGP-3): comparison between normal and nude mice.

Various lymphoid cells obtained from BALB/c and BALB/c nu/nu mice were cultured in vitro with recombinant human interleukin 2 (rIL 2), and the characteristics of responder cells to rIL 2 were analyzed. Spleen cells, lymph node cells, and thymocytes except for bone marrow cells obtained from BALB/c mice remarkably proliferated in response to rIL 2. On the other hand, among lymphoid cells obtained from BALB/c nu/nu mice, only lymph node cells showed significant proliferation by rIL 2. Flow cytometric analyses revealed that mainly two types of lymphoid cells were proliferating in response to rIL 2 in BALB/c mice, i.e., Thy 1+, Lyt 1−, Lyt 2− and Thy 1+, Lyt 1−, Lyt 2+ cells. On the other hand, most of the proliferating cells were Thy 1+, Lyt 1−, Lyt 2− cells in BALB/c nu/nu mice. Treatment with various antibodies plus complement revealed that the majority of IL 2‐responsive cells in BALB/c mice were Thy 1+, Lyt 1+, and Lyt 2+, although a minor part of them were Thy 1−, Lyt 1−, and Lyt 2−. On the other hand, a predominant type of the IL 2‐responsive cells in BALB/c nu/nu mice were Thy 1−, Lyt 1−, and Lyt 2−, though some were Thy 1+. Nonspecific killer activity against tumor cells increased to variable extents in all of the lymphoid cells of both strains after culture with rIL 2. Our results indicate that mouse responder cells to rIL 2 have the following characteristics. First, the responder cells exist abundantly among spleen, lymph nodes, and thymus in normal mice, though their cell lineages are heterogeneous; one is of T cell lineage and the other of natural killer (NK) cell lineage. Second, nude mice are defective in the responder cells of T cell lineage but not of NK cell lineage. Moreover, the responder cells in nude mice predominantly accumulate in the lymph nodes but not other lymphoid organs.