Short-term administration of recombinant human erythropoietin decreases B cell number in human peripheral blood.

OBJECTIVES: There are conflicting results on the influence of recombinant human erythropoietin (rHuEPO) administration to lymphocytes, especially to B cells. METHODS: We analyzed peripheral white blood cell (WBC) subsets in patients who received one bolus administration of rHuEPO. 119 autologous blood donors were enrolled in this study. Fourty-nine out of them were treated with rHuEPO. Blood samples were obtained before the first phlebotomy and one week later before the second one. By flow cytometry, we measured the numbers of WBC, lymphocytes, dendritic cells, CD4+ T cells, CD8+ T cells, natural killer (NK) cells, B cells, monocytes, and neutrophils, further details of B cell subsets. RESULTS: In the EPO-treatment group, absolute numbers of lymphocytes, especially CD8+ T cells, NK cells, and B cells, significantly decreased after rHuEPO administration. In B cell subsets, absolute numbers of naïve B cells and IgD-CD27- B cells significantly decreased. Other B cell subsets, such as transitional B cells, memory B cells, and marginal zone B cells, also showed a decreasing trend. CONCLUSION: These findings suggest that a single administration of rHuEPO can influence human immune system via reduction of B cell number in peripheral blood.

[Successful treatment with dasatinib for polycythemia vera patient emerging BCR-ABL positive clone during 13 years of treatment].

Herein, we report a patient with polycythemia vera (PV) who exhibited Philadelphia chromosome (Ph) positive CML-like clinical features after 13 years of hydroxycarbamide administration and successful treatment with a tyrosine kinase inhibitor (TKI). She was 64 years old when initially diagnosed with PV and was confirmed to be negative for BCR-ABL translocation. Thirteen years later, with increasing white blood cell and platelet counts, a BCR-ABL positive clone emerged and the JAK2V617F mutation disappeared. After TKI treatment, the BCR-ABL copy number decreased and the JAK2V617F mutation was again detected. Furthermore, MPN clinical features were observed. This case provides insights into the clonal divergence and growth advantage of the Ph positive clone over the MPN clone. Whether JAK2V617F is an MPN initiating event or a secondary mutation has been a point of discussion for the past several years. This issue is also considered in the present report.

[IgM-lambda multiple myeloma presenting with systemic amyloidosis].

A 59-year-old man was referred to our hospital due to nephrotic syndrome with IgM paraproteinemia. Physical examination demonstrated marked hepatomegaly and anasarca. Serum M-protein was 0.94 g/dl and urinary analysis detected the presence of Bence Jones protein. Bone marrow plasma cell count was 11.2%. Histological examination demonstrated AL-type amyloid deposition in the liver, kidneys, bone marrow, stomach and rectum. These findings led to a diagnosis of IgM multiple myeloma with systemic amyloidosis. Although there was no apparent response to 2 courses of vincristine, doxorubicin and dexamethasone (VAD) regimen, subsequent treatment with bortezomib in combination with dexamethasone resulted in a rapid reduction in M protein to 0.49 g/dl, approximately half the pre-treatment level.

Successful treatment with reduced-intensity stem cell transplantation for secondary myelofibrosis following polycythemia vera.

Ten years after being diagnosed with polycythemia vera, a 55-year-old woman required frequent blood transfusion due to secondary myelofibrosis. She underwent reduced-intensity stem cell transplantation (RIST) from an HLA-identical sibling donor. Since mixed chimerae were identified in the peripheral blood at day 35, cyclosporine was withdrawn. At day 73, she developed acute graft-versus-host disease of the liver, while simultaneous resolution of splenomegaly occurred and complete donor chimerism in the peripheral blood was achieved. Frequent red blood cell transfusion was required until day 300 after transplantation. Thus, RIST for an older patient with secondary myelofibrosis was successful without severe treatment-related morbidity. This case suggests that RIST could be an effective treatment modality for secondary myelofibrosis.

[Development of an extramedullary plasmacytoma despite disappearing M protein in multiple myeloma by bortezomib treatment].

A 65-year-old male with IgG-kappa multiple myeloma was treated with melphalan-prednisolone (MP) and obtained a minimal response. Five months after the initiation of MP, he developed back pain, renal failure, hypercalcemia and increased plasma cells in the bone marrow. He was treated with bortezomib. After 2 cycles, he developed a peripheral neuropathy, and the dose of bortezomib was decreased to 1.0 mg/m(2). After 5 cycles, serum monoclonal protein was not detected by immunofixation, and the percentage of bone marrow plasma cells decreased to less than 5%. In March 2007, he developed lumbago again, and MRI of the lumbar vertebrae showed a tumor at the para pediculus arcus vertebrae. Immunohistochemistry of the biopsied tumor demonstrated monoclonal plasma cell infiltration. The patient was treated with local radiation therapy. Bortezomib is a new and effective agent for refractory/relapsed multiple myeloma. It has also been reported that bortezomib is effective for solitary extramedullary plasmacytoma (EMP). However, in the patient reported here, although bortezomib induced a complete response with regard to the serum monoclonal protein and the percentage of bone marrow plasma cells, EMP developed in the parapediculus arcus vertebrae. Herein, we document a case of EMP development during successful bortezomib therapy.

X-linked agammaglobulinemia diagnosed in adulthood: a case report.

X-linked agammaglobulinemia (XLA) is a humoral immunodeficiency caused by mutations in Bruton's tyrosine kinase (BTK). Patients typically become symptomatic during infancy or early childhood and develop recurrent bacterial infections. We report a Japanese case of XLA diagnosed in a patient who was 27 years of age and who had no history of severe infection. The patient's serum immunoglobulin (Ig) G, IgA, and IgM levels were 132,7, and 17 mg/dL, respectively. The percentage of positive cells for CD19 and CD20 was 0.03% and 0.02%, respectively. The patient's brother and sister had no abnormalities. Flow cytometric analysis showed a partially reduced expression of BTK protein in the patient's peripheral monocytes. Sequencing of the BTK. gene revealed a missense mutation (230C>T,T33I). Given this data, this patient was diagnosed as having rare, late onset XLA with a missense mutation in the BTK gene.

Regulation by Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 of alpha-galactosylceramide-induced antimetastatic activity and Th1 and Th2 responses of NKT cells.

Interaction of alpha-galactosylceramide (alpha-GalCer) presented by CD1d on dendritic cells (DCs) with the invariant TCR of NKT cells activates NKT cells. We have now investigated the role of Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 (SHPS-1), a transmembrane protein abundantly expressed on DCs, in regulation of NKT cells with the use of mice that express a mutant form of SHPS-1. The suppression by alpha-GalCer of experimental lung metastasis was markedly attenuated in SHPS-1 mutant mice compared with that apparent in wild-type (WT) mice. The antimetastatic effect induced by adoptive transfer of alpha-GalCer-pulsed DCs from SHPS-1 mutant mice was also reduced compared with that apparent with WT DCs. Both the production of IFN-gamma and IL-4 as well as cell proliferation in response to alpha-GalCer in vitro were greatly attenuated in splenocytes or hepatic mononuclear cells from SHPS-1 mutant mice compared with the responses of WT cells. Moreover, CD4+ mononuclear cells incubated with alpha-GalCer and CD11c+ DCs from SHPS-1 mutant mice produced markedly smaller amounts of IFN-gamma and IL-4 than did those incubated with alpha-GalCer and CD11c+ DCs from WT mice. SHPS-1 on DCs thus appears to be essential for alpha-GalCer-induced antimetastatic activity and Th1 and Th2 responses of NKT cells. Moreover, our recent findings suggest that SHPS-1 on DCs is also essential for the priming of CD4+ T cells by DCs.

Resistance to experimental autoimmune encephalomyelitis and impaired T cell priming by dendritic cells in Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 mutant mice.

Src homology 2 domain-containing protein tyrosine phosphatase (SHP) substrate-1 (SHPS-1) is a transmembrane protein that binds the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is expressed on the surface of CD11c(+) dendritic cells (DCs) and macrophages. In this study, we show that mice that express a mutant form of SHPS-1 lacking most of the cytoplasmic region are resistant to experimental autoimmune encephalomyelitis (EAE) in response to immunization with a peptide derived from myelin oligodendrocyte glycoprotein (MOG (35-55)). The MOG (35-55)-induced proliferation of, and production of IFN-gamma, IL-2, and IL-17, by T cells from immunized SHPS-1 mutant mice were reduced compared with those apparent for wild-type cells. The abilities of splenic DCs from mutant mice to stimulate an allogenic MLR and to prime Ag-specific T cells were reduced. Both IL-12-stimulated and TLR-dependent cytokine production by DCs of mutant mice were also impaired. Finally, SHPS-1 mutant mice were resistant to induction of EAE by adoptive transfer of MOG (35-55)-specific T cells. These results show that SHPS-1 on DCs is essential for priming of naive T cells and the development of EAE. SHPS-1 is thus a potential therapeutic target in inflammatory disorders of the CNS and other autoimmune diseases.

Enhanced phagocytosis of CD47-deficient red blood cells by splenic macrophages requires SHPS-1.

The interaction of CD47 on red blood cells (RBCs) with SHPS-1 on macrophages is implicated to prevent the phagocytosis of the former cells by the latter cells. Indeed, the rate of clearance of transfused CD47-deficient (CD47(-/-)) RBCs from the bloodstream of wild-type mice was markedly increased compared with wild-type RBCs. Conversely, the rate of clearance of transfused wild-type RBCs was markedly increased in mice that expressed a mutant form of SHPS-1 lacking most of the cytoplasmic region of the protein. However, we here found that the clearance of CD47(-/-) RBCs in SHPS-1 mutant mice was minimal. In addition, the phagocytosis of CD47(-/-) RBCs by splenic macrophages from SHPS-1 mutant mice was markedly reduced compared with wild-type macrophages. These results thus suggest an additional role for CD47 on RBCs in the negative regulation of phagocytosis by macrophages and in determination of the life span of circulating RBCs.

SHPS-1 promotes the survival of circulating erythrocytes through inhibition of phagocytosis by splenic macrophages.

The lifespan of circulating red blood cells (RBCs) produced in bone marrow is determined by their elimination through phagocytosis by splenic macrophages. The mechanism by which RBC elimination is regulated has remained unclear, however. The surface glycoprotein SHPS-1, a member of the immunoglobulin superfamily, is abundant in macrophages. We have now examined the regulation of RBC turnover with the use of mice that express a mutant form of SHPS-1 lacking most of its cytoplasmic region. The mutant mice manifested mild anemia as well as splenomegaly characterized by expansion of the red pulp. The numbers of erythroid precursor cells in the spleen and of circulating reticulocytes were also increased in the mutant mice. In contrast, the half-life of circulating RBCs was reduced in these animals, and the rate of clearance of injected opsonized RBCs from the peripheral circulation was increased in association with their incorporation into splenic macrophages. Phagocytosis of opsonized RBCs by splenic macrophages from mutant mice in vitro was also increased compared with that observed with wild-type macrophages. These results suggest that SHPS-1 negatively regulates the phagocytosis of RBCs by splenic macrophages, thereby determining both the lifespan of individual RBCs and the number of circulating erythrocytes.