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Haruo Nagumo,
Jun Abe,
Hirotsugu Kano,
Shinsuke Taki,
Kazuko Yamazaki,
Takashi Yamazaki,
Norimoto Kobayashi,
Kenichi Koike,
Kazuo Sugane,
Hirohisa Saito,
Kazunaga Agematsu
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ABSTRACT: The molecular mechanisms involving in B-cell survival/proliferation are poorly understood. Here we investigated the molecules affecting the survival of human naïve and memory B cells. Without stimulation, naïve B cells survived longer than memory B cells. Moreover, the viability of memory B cells decreased more rapidly than that of naïve B cells following with Staphylococcus aureus Cowan strain (SAC), anti-immunoglobulin (Ig), or anti-CD40 stimulation, but displayed the same levels of survival following CpG DNA stimulation. We analyzed the transcriptional differences between B-cell subsets by gene expression profiling, and identified 15 genes significantly correlated to survival/proliferation. Among them, IL-21 receptor (IL-21R) and T-cell leukemia 1 (TCL1) proto-oncogene were highly expressed in naïve B cells. IL-21 induced the proliferation of both naïve and memory B cells. Marked phosphorylation of Akt was found in naïve B cells compared with memory B cells. This study suggests that naive and memory B cells are regulated by several distinct molecules, and the IL-21R and TCL1/Akt pathways might play crucial roles in naïve B cells for their maintenance.
Cellular Immunology 03/2009; 256(1-2):56-63. · 1.97 Impact Factor
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Norimoto Kobayashi,
Piia Karisola,
Victor Peña-Cruz,
David M Dorfman,
Masahisa Jinushi,
Sarah E Umetsu,
Manish J Butte, Haruo Nagumo,
Irene Chernova,
Baogong Zhu,
Arlene H Sharpe,
Susumu Ito,
Glenn Dranoff,
Gerardo G Kaplan,
Jose M Casasnovas,
Dale T Umetsu,
Rosemarie H Dekruyff,
Gordon J Freeman
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ABSTRACT: The T cell immunoglobulin mucin (TIM) proteins regulate T cell activation and tolerance. Here we showed that TIM-4 is expressed on human and mouse macrophages and dendritic cells, and both TIM-4 and TIM-1 specifically bound phosphatidylserine (PS) on the surface of apoptotic cells but not any other phospholipid tested. TIM-4(+) peritoneal macrophages, TIM-1(+) kidney cells, and TIM-4- or TIM-1-transfected cells efficiently phagocytosed apoptotic cells, and phagocytosis could be blocked by TIM-4 or TIM-1 monoclonal antibodies. Mutations in the unique cavity of TIM-4 eliminated PS binding and phagocytosis. TIM-4 mAbs that blocked PS binding and phagocytosis mapped to epitopes in this binding cavity. These results show that TIM-4 and TIM-1 are immunologically restricted members of the group of receptors whose recognition of PS is critical for the efficient clearance of apoptotic cells and prevention of autoimmunity.
Immunity 01/2008; 27(6):927-40. · 21.64 Impact Factor
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ABSTRACT: B cells can differentiate into antibody-secreting plasma cells, however the signals that control the entry into this pathway are not clearly understood. We have investigated the role of human CD72 in mature B cell differentiation. Human CD72 is preferentially expressed in naive B cells, but marginal levels of expression can be found in switched memory B cells. CD72 cross-linking promoted an increase in B cell activation and proliferation. Interestingly, expression of CD27, whose signal induces the differentiation of B cells into plasma cells, was down-modulated by CD72 stimulation. This CD72 signaling also induced tyrosine phosphorylation of various proteins such as Blk. Plasma cell differentiation and Ig syntheses were diminished by CD72 ligation in the presence of Staphylococcus aureus Cowan strain (SAC) plus IL-2 but not in the presence of CD40 signaling or CpG oligodeoxynucleotide. Our results show that CD72 signaling reduces the expression of X-box binding protein 1 in B cells stimulated with SAC plus IL-2, but the expression of PRDI-BF1 was unaffected. Taken together, these data demonstrate that CD72 is a key molecule in regulating mature B cell differentiation, particularly in preventing the differentiation of naive B cells into plasma cells, thus blocking the production of low-affinity antibodies.
European Journal of Immunology 09/2005; 35(8):2325-34. · 5.10 Impact Factor
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ABSTRACT: B cells can differentiate into antibody-secreting plasma cells, however the signals that control the entry into this pathway are not clearly understood. We have investigated the role of human CD72 in mature B cell differentiation. Human CD72 is preferentially expressed in naive B cells, but marginal levels of expression can be found in switched memory B cells. CD72 cross-linking promoted an increase in B cell activation and proliferation. Interestingly, expression of CD27, whose signal induces the differentiation of B cells into plasma cells, was down-modulated by CD72 stimulation. This CD72 signaling also induced tyrosine phosphorylation of various proteins such as Blk. Plasma cell differentiation and Ig syntheses were diminished by CD72 ligation in the presence of Staphylococcus aureus Cowan strain (SAC) plus IL-2 but not in the presence of CD40 signaling or CpG oligodeoxynucleotide. Our results show that CD72 signaling reduces the expression of X-box binding protein 1 in B cells stimulated with SAC plus IL-2, but the expression of PRDI-BF1 was unaffected. Taken together, these data demonstrate that CD72 is a key molecule in regulating mature B cell differentiation, particularly in preventing the differentiation of naive B cells into plasma cells, thus blocking the production of low-affinity antibodies.
European Journal of Immunology 07/2005; 35(8):2325 - 2334. · 5.10 Impact Factor
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Sarah E Umetsu,
Wan-Ling Lee,
Jennifer J McIntire,
Laura Downey,
Bharati Sanjanwala,
Omid Akbari,
Gerald J Berry, Haruo Nagumo,
Gordon J Freeman,
Dale T Umetsu,
Rosemarie H DeKruyff
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ABSTRACT: We have examined the function of TIM-1, encoded by a gene identified as an 'atopy susceptibility gene' (Havcr1*), and demonstrate here that TIM-1 is a molecule that costimulates T cell activation. TIM-1 was expressed on CD4(+) T cells after activation and its expression was sustained preferentially in T helper type 2 (T(H)2) but not T(H)1 cells. In vitro stimulation of CD4(+) T cells with a TIM-1-specific monoclonal antibody and T cell receptor ligation enhanced T cell proliferation; in T(H)2 cells, such costimulation greatly enhanced synthesis of interleukin 4 but not interferon-gamma. In vivo, the use of antibody to TIM-1 plus antigen substantially increased production of both interleukin 4 and interferon-gamma in unpolarized T cells, prevented the development of respiratory tolerance, and increased pulmonary inflammation. Our studies suggest that immunotherapies that regulate TIM-1 function may downmodulate allergic inflammatory diseases.
Nature Immunology 06/2005; 6(5):447-54. · 26.01 Impact Factor
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ABSTRACT: We have observed a male infant with severe combined immunodeficiency (SCID) responsible for Artemis gene mutation, in whom marked expansion of the transplacentally grafted maternal CD4(+) T cells was observed in various tissues. His class I and II major histocompatibility antigens (MHC) were identical to his mother's. We analyzed the T-cell populations within target tissues at a molecular level in order to determine whether different T-cell clonotypes are expanded in different types of tissue. Prior to T-cell expansion, the T-cell receptor variable beta (TCRBV) 5.1 subfamily predominated in peripheral blood (PB) lymphocytes. Third complementarity determining region (CDR3) size spectratyping and amino acid sequencing showed that the range of T-cell clonotypes was very restricted. After T-cell expansion, different TCRBV subfamilies were found to predominate in different target tissues; these included TCRBV 5.1 and 17 in the PB, TCRBV 13 and 21.3 in the bone marrow, and TCRBV 17 in lymph nodes. CDR3 size analysis showed that the expression of different proliferating T-cell clonotypes remained restricted after T-cell expansion. These results indicate that highly restricted maternal T-cell clonotypes can markedly expand, possibly in response to tissue-specific antigens, in a MHC-identical recipient.
Clinical Immunology 09/2003; 108(2):159-66. · 4.05 Impact Factor
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ABSTRACT: Phosphoinositide 3-kinases (PI3Ks) constitute a family of lipid kinases that regulate an array of fundamental cellular responses by neutrophils [polymorphonuclear leukocytes (PMN)]. p85alpha Gene-disrupted mice were used to help accurately identify the physiological role of the PI3K isoform in PMN activation in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF). PMN from the p85alpha-/- mice showed normal cellular motility, and the quantity of superoxide anion (O(2(-))) produced by PMN upon stimulation with formyl-Met-Leu-Phe did not significantly differ between p85alpha-/- and wild-type mice under controlled conditions. In p85alpha-/- mice, the O(2(-)) production by PMN was enhanced (primed) by GM-CSF when stimulated with the chemotactic peptide but to a significantly lesser extent than in wild-type mice. In addition, no major GM-CSF-dependent delay in apoptosis or activation of Akt protein phosphorylation by GM-CSF was observed in the p85alpha-/- mice. In terms of targeting strategy, however, the mutation actually expressed a small amount of Ia-type (p85alpha-regulated) PI3K activity (partially abrogated) in the mice. These results demonstrate that Ia-type PI3K plays a critical role in the enhancement of the GM-CSF-modulated function of PMN and in the PI3K/Akt pathway-dependent delay of PMN apoptosis.
Journal of Leukocyte Biology 12/2002; 72(5):1020-6. · 4.99 Impact Factor
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ABSTRACT: We describe 3 Japanese patients in 2 families with familial Mediterranean fever (FMF) as determined by gene analysis. FMF is an ethnically related, genetic disease, occurring commonly in some Mediterranean populations. The FMF gene (MEFV) mutation found in our patients is M694I. The patients may be remote from East Asian extraction.
The Journal of Rheumatology 07/2002; 29(6):1324-5. · 3.69 Impact Factor
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ABSTRACT: Autoimmune neutropenia of infancy (ANI) is a common form of chronic childhood neutropenia, which is caused by antineutrophil antibodies. The syndrome is characterized by a severe selective neutropenia accompanied with recurrent bacterial infections.
We investigated 10 ANI patients in our hospital. Neutropenia in ANI patients was found in patients aged between 9 and 19 months. They had no life-threatening infections and their infections episode could be controlled by the conventional antibiotic therapy in general. The correlation of absolute neutrophil counts (ANC) and neutrophil-associated immunoglobulin (NAIg) levels in each case was analyzed and their clinical courses followed.
The NAIg levels were high in all cases at the diagnosis, however, they had no relationship with ANC. The severity of infection and the period of neutropenia in our patients have no correlation to NAIg levels either. In our four cases, neutropenia disappeared after a median of 26 months (range, 18-29 months). The periods of neutropenia were nearly similar to previous reports. After the NAIg level began to wane, neutrophil counts increased in four patients whose neutrophil counts had recovered finally.
Detection of NAIg is useful for the diagnosis, and the observation of changes in NAIg may be helpful one by one for prediction of the prognosis.
Pediatrics International 07/2002; 44(3):269-72. · 0.63 Impact Factor
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ABSTRACT: The relationship between class switch recombination (CSR) and somatic hypermutation has been unclear. By using human CD27(-) naive B cells, we investigated the somatic hypermutation and producibility of immunoglobulins (Igs) that occur after CSR. Although neither adult CD27(-) nor cord blood B cells, which showed the unmutated Ig V-region genes, produced IgG, IgM, or IgA in response to conventional stimuli, they produced IgG and IgM but not IgA in the presence of Staphylococcus aureus Cowan strain (SAC) + interleukin-2 (IL-2) + IL-10 + anti-CD40 mAb + CD32 transfectants (CD40/CD32T). The naive B cells also produced IgE when combined with IL-4 + CD40/CD32T. In parallel with IgG production, the expression of mature gamma1 and gamma 2 transcripts was induced from naive B cells by the stimuli. The CD27 expression on human naive B cells was induced remarkably by CD40 signaling or B-cell receptor engagement, but somatic hypermutation could not be induced. The proliferation and differentiation into plasma cells were induced from naive B cells, whereas most of the plasma cells displayed very low levels of mutations in Ig V-region genes. CD27(-) naive B cells expressed activation-induced cytidine deaminase messenger RNA by the stimuli later than CD27(+) memory B cells. Our results demonstrate that CSR, but not noticeable somatic hypermutation, can be induced from CD27(-) naive B cells upon B-cell receptor engagement and CD40 signaling in cooperation with cytokines, suggesting that CSR and somatic hypermutation processes can occur independently, and the antibodies produced in this in vitro system are low-affinity antibodies.
Blood 02/2002; 99(2):567-75. · 9.90 Impact Factor
