Hirosuke Yagura

Demonstration of high-affinity interleukin-2 receptors on B-chronic lymphocytic leukemia cells: functional and structural characterization.

SummaryFunctional and structural characteristics of interleukin 2 (IL-2) receptors on B-cell chronic lymphocytic leukemia (B-CLL) cells were analyzed by a proliferation assay, IL-2 binding assay and cross-linking study. In the3H-thymidine incorporation assay, purified B-CLL cells from four out of sixteen cases, in which the percentage of Tac antigen (Tac Ag) positive cells in peripheral blood lymphocytes ranged from 0 to 48.8%, responded to IL-2 (100 U/ml) after both 3- and 6-day incubation. No relationship was found between the responsiveness to IL-2 and the percentage of Tac Ag positive cells. In the radiolabeled IL-2 binding assay, however, B-CLL cells from all seven cases examined, including three cases with mitogenic response to IL-2 and four cases without mitogenic response, were shown to have both high- and low-affinity receptors. The number of high- and low-affinity receptors per cell ranged from 29–186 and from 420 to 1,800, respectively. Furthermore, with the affinity cross-linking method p55 (Tac Ag) and p70/75 were found even in cases without mitogenic response in their B-CLL cells. In conclusion, the B-CLL cells so far examined possessed high-affinity IL-2 receptors consisting of p55 and p70/75; nevertheless, this was not sufficient to respond to the mitogenic signal of IL-2.

Analysis of surface antigen expression of human immunoglobulin‐secreting cells: phenotypic heterogeneity in normal counterparts of myeloma cells

Human myeloma cells are malignant counterparts of plasma cells which represent the most differentiated B cells. Myeloma cells are, however, heterogeneous in their surface antigen expression (Katagiri et al, 1984, 1985), which may reflect that normal plasma cells have a spectrum of differentiation. To test this hypothesis, immunoglobulinsecreting cells (ISC) of non‐neoplastic nature were studied with regard to their surface antigen expression by using a combination of reverse haemolytic plaque assay and complement‐dependent cytolysis. Non‐neoplastic ISC were found to have a broad spectrum of differentiation stages from the immature type of CD20+, HLA‐DR+, CD38+ in the peripheral blood to the mature type of CD20–, HLA‐DR–, CD38+ in the bone marrow. In patients with polyclonal B cell activation (PBA), ISC showed a more immature antigen expression in comparison with ISC in normal controls or patients without PBA. The surface antigen development of ISC was clearly demonstrated throughout the stages in the analysis of mitogen‐induced ISC in vitro. No significant difference in the surface phenotype of ISC was found among heavy chain classes. Thus, non‐neoplastic ISC show a spectrum of differentiation similar to that of myeloma cells, depending on the site where ISC are located, and on the degree of PBA in vivo.

High-affinity interleukin 2 receptors on B cell chronic lymphocytic leukemia cells are induced by phorbol myristate acetate but not by calcium ionophore

The role of phorbol myristate acetate (PMA: a protein kinase-C (PKC) activator) and calcium ionophore A23187 in the induction mechanism of the interleukin 2 receptor (IL2R) on B-cell chronic lymphocytic leukemia (B-CLL) cells was studied. B-CLL cells from five patients were cultured with PMA or A23187 for 72 h and used for the following experiments. Interleukin 2 (IL2) cross-linking assays showed that PMA induced the expression of IL2R subunits (p55 and p70/75) in all cases examined, but that A23187 induced neither subunit. Radiolabeled IL2 binding assays also demonstrated that PMA induced both high-affinity IL2R (HA-IL2R) and low-affinity IL2R (LA-IL2R) on B-CLL cells, but that A23187 did not. After treatment with PMA, three of five cases did not respond to IL2 even though they expressed HA-IL2R, suggesting impaired signal transduction. No cases responded to IL2 after treatment with A23187. In conclusion, PMA but not A23187 stimulates B-CLL cells to induce the expression of p55 and p70/75, indicating that the PKC pathway plays a more important role than the calcium pathway in the induction of IL2R subunits in B-CLL cells.

Early Trilineage Recovery by Granulocyte Colony-Stimulating Factor in a Patient with Aplastic Anemia

Dr. Yuzuru Kanakura, Second Department of Internal Medicine, Osaka University Medical School, Yamadaoka 2-2, Suita Osaka 565 (Japan) Among the cytokines active in hematopoiesis, granulocyte colony-stimulating factor (G-CSF) has functions mainly on cells of neutrophilic granulocyte lineage [1]. A large number of clinical trials have suggested that G-CSF can accelerate the recovery of neutrophils when used after high-dose cytotoxic chemotherapy or bone marrow transplantation [2, 3]. In addition, G-CSF have been shown to have beneficial effects in patients with aplastic anemia (AA) who suffer from severe neutropenia [4]. With the exception of rare instances, however, G-CSF is known to have little or no effect on erythrocyte or platelet counts [2, 4-7]. We report here a unique case with acquired AA who showed trilineage recovery shortly after administration of rhG-CSF. Case Report A 57-year-old man was referred to Osaka University Hospital because of pancytopenia in April 1993. He had a 3-month history of pancytopenia and had received a total of 800 ml of red blood cell (RBC) in a previous hospital. Laboratory data were as follows: hemoglobin (Hb), 11.2 g/dl (immediately after RBC transfusion); reticulo-cytes88 × 109/1, white blood cells (WBC), 3.2 × 109/1 with differentials of 35% neutrophils and 56% lymphocytes; and platelets (PLT) 73 × 109/1. Bone marrow aspirate and biopsy revealed uniform hypocellularity (nucleated cell count, 14 × 109/l)withnomegakaryo-cytes and no morphological abnormalities. Based on these findings, he was diagnosed as having mild AA [8]. Daily anabolic steroids were thus administered orally at a dose of 30 mg/kg body weight in April 1993. This treatment did not improve the hematologic parameters and hemoglobin decreased (fig. 1). Because RBC transfusions were required every 2 or 4 weeks, the patient was admitted to our hospital on September 21, 1993. Hemoglobin was 8.6 g/dl, reticulocytes 80 × 109/1, WBC 2.71 × 109/1 (47.8% neutrophils, 3.8% eosinophils, 39.9% lymphocytes, 8.1% monocytes), and PLT