Kouji Fujimoto

Effect of recombinant human interleukin-11 on rat megakaryopoiesis and thrombopoiesis in vivo : comparative study with interleukin-6

Summary. The ability of recombinant human interleukin‐11 (IL‐11) to stimulate rat megakaryopoiesis and thrombopoiesis in vivo was investigated. Once daily subcutaneous injections of IL‐11 at doses of 2, 8 and 20 μg/rat for 5 d caused dose‐dependent increases in platelet counts. The chronic administration of 20 μg/rat/d for 14 d resulted in biphasic increases in platelet counts with peaks at days 8 and 15 of up to 30% over the control, continuing for more than 5 d after cessation of IL‐11 injections. Moreover, a striking increase in megakaryocytic size and ploidy in bone marrow in response to IL‐11 was elicited. IL‐11 induced a dose‐dependent elevation in bone marrow cell numbers but not in splenic weight and cell numbers. Modifications of these parameters were noted as soon as 24 h after the first IL‐11 injections. IL‐11 had a same potency of thrombopoietic effect in rats as compared with IL‐6. However, elevation of acute phase protein such as immunosuppressive acidic protein was 2–2‐fold in rats given 20 μg/d of IL‐6 over those receiving a same dose of IL‐11 (470 v 210 μg/ml). In addition, the rate of body‐weight increase in rats receiving IL‐11 for 5 d as well as 14 d did not differ from that in control animals. In IL‐6 treated rats, the increase in body weight was significantly slower than the controls, which was observed even in the group given 8 μg/d of IL‐6. These results suggest that IL‐11 may be an effective strategy for the treatment of thrombocytopenia.

The expression of functional erythropoietin receptors on an interleukin-3 dependent cell line

We report the expression of the erythropoietin receptors on an interleukin-3 dependent cell line. By the transfer into medium supplemented with erythropoietin, DA-1 cells were converted to an erythropoietin dependent growth state. [125I] erythropoietin was used to detect receptors specific for this hormone on the cell surface. Binding studies revealed that erythropoietin bound to 131 +/- 23 receptors/cell with a Kd of 0.54 +/- 0.2 nM. When the cells were incubated at 37 degrees C, trichloroacetic acid soluble radioactivity appeared in the medium after [125I] erythropoietin binding began to decrease, suggesting that the decline represents the degradation of cell associated [125I] erythropoietin- receptor complexes.

Cloning of interleukin 2 mRNAs from human tonsils

Human interleukin 2 (IL-2) mRNAs were cloned from a cDNA library prepared from mitogen-stimulated tonsillar mononuclear cells. One of these clones was sequenced and, using this cDNA as a hybridization probe, Southern blot analysis of the human placental DNA was performed. Our results indicate that there is only one IL-2 gene in the human genome.

Dissection of the Role of Macrophages in Triggering T Lymphocytes for Interleukin 2 Production by Monoclonal Antibody OKT3

Unfractionated human peripheral blood mononuclear cells produce a small amount of interleukin 2 (IL 2) by stimulation with a monoclonal anti‐T3 antibody (OKT3) in vitro. The IL 2 production could be greatly augmented by the addition of a phorbol ester, 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA).

Translation of Human Interleukin 2 mRNA in Xenopus laevis Oocytes

Poly(A)‐positive mRNA extracted from tonsillar mononuclear cells stimulated with phytohemagglutinin‐M and 12‐o‐tetradecanoyl phorbol 13‐acetate was successfully translated into biologically active interleukin 2 (IL‐2) in Xenopus laevis oocytes, and secreted into the incubation medium. In control experiments, the extract of oocytes injected with either poly(A)‐negative RNA or buffer did not show any IL‐2 activity. By sucrose density gradient centrifugation analysis, IL‐2 mRNA was found as a single peak corresponding to a sedimentation coefficient of 10‐11S.