Koji Shinozaki

Absence of IgD-CD27(+) memory B cell population in X-linked hyper-IgM syndrome.

The present study analyzed peripheral blood B cell populations separated by IgD and CD27 expression in six males with X-linked hyper-IgM syndrome (XHIM). Costimulation of mononuclear cells from most of the patients induced no to low levels of class switching from IgM to IgG and IgA with Staphylococcus aureus Cowan strain (SAC) plus IL-2 or anti-CD40 mAb (anti-CD40) plus IL-10. Measurable levels of IgE were secreted in some of the patients after stimulation with anti-CD40 plus IL-4. Costimulation with SAC plus IL-2 plus anti-CD40 plus IL-10 yielded secretion of significant levels of IgG in addition to IgM, but not IgA. The most striking finding was that peripheral blood B cells from all of the six patients were composed of only IgD+ CD27(-) and IgD+ CD27(+) B cells; IgD- CD27(+) memory B cells were greatly decreased. IgD+ CD27(+) B cells from an XHIM patient produced IgM predominantly. Our data indicate that the low response of IgG production in XHIM patients is due to reduced numbers of IgD- CD27(+) memory B cells. However, the IgG production can be induced by stimulation of immunoglobulin receptors and CD40 in cooperation with such cytokines as IL-2 and IL-10 in vitro.

Theophylline induces neutrophil apoptosis through adenosine A2A receptor antagonism.

This study was designed to determine whether theophylline would augment granulocyte apoptosis via a mechanism of adenosine A2A receptor antagonism. A selective adenosine A2 receptor agonist (CGS‐21680, 1 μM) exhibited the most efficient potency for decreasing neutrophil apoptosis for 16 h from 63 ± 5 to 19 ± 4% (P < 0.001); it exerted poor and adverse effects on eosinophil survival. A selective protein kinase A inhibitor KT‐5720 (10 μM) reversed the capacity of dibu‐tyryl cAMP but not CGS‐21680 to induce an inhibitory effect on neutrophil apoptosis, suggesting that occupancy of adenosine A2 receptors inhibit neutrophil apoptosis by a cAMP‐independent mechanism. Theophylline derivatives show the following pattern of potency for inducing neutrophil apoptosis competing with CGS‐21680: 8‐phenyltheophylline = 8‐p‐sulfophenyltheophylline > theophylline ≫ enprofylline. This pattern is consistent with the affinity established for A2A receptors. Theophylline demonstrated an additive effect to that of anti‐Fas antibody (CH11, 1 μg/mL) in inducing neutrophil apoptosis, but not to that of adenosine deaminase or KF‐17837 (a selective A2 receptor antagonist; 1 μM), suggesting conflicting effects on the receptor antagonism. These findings suggest that theophylline has an immunomodulatory action on neutrophil apoptosis via a mechanism of A2A antagonism. J. Leukoc. Biol. 67:529–535; 2000.

Plasma Cell Generation from B-Lymphocytes via CD27/CD70 Interaction

To produce antibodies, the differentiation of B cells into antibody-secreting cells, plasma cells, is required. We describe that ligation of CD27, which belongs to the tumor necrosis factor receptor (TNFR) family and is a memory marker of B cells, yields crucial signals that positively control the entry of B cells into the pathway to plasma cells. The triggering via CD27 by CD27 ligand (CD70) on purified peripheral blood B cells yielded an increase in the number of plasma cells in the presence of interleukin-10 (IL-10). The differentiation into plasma cells by a combination of IL-10 and CD70-transfectants occurred in CD27+ B cells, but not in CD27- B cells. Moreover, the addition of IL-2 to the IL-10 and CD70-transfectants greatly induced the differentiation into plasma cells. In the presence of only IL-2, IL-4 or IL-6, CD70-transfectants did not promote the differentiation into plasma cells. On the other hand, CD40 signaling increased the expansion of a B cell pool from peripheral blood B cells primarily activated by IL-2, IL-10 and anti-CD40 mAb. These data demonstrate that CD27 ligand (CD70) is a key molecule to direct the differentiation of CD27+ memory B cells toward plasma cells in cooperation with IL-10.

An Increase in Circulating Mast Cell Colony-Forming Cells in Asthma

We compared a potential to generate mast cells among various sources of CD34+ peripheral blood (PB) cells in the presence of stem cell factor (SCF) with or without thrombopoietin (TPO), using a serum-deprived liquid culture system. From the time course of relative numbers of tryptase-positive and chymase-positive cells in the cultured cells grown by CD34+ PB cells of nonasthmatic healthy individuals treated with G-CSF, TPO appears to potentiate the SCF-dependent growth of mast cells without influencing the differentiation into mast cell lineage. CD34+ PB cells from asthmatic patients in a stable condition generated significantly more mast cells under stimulation with SCF alone or SCF+TPO at 6 wk of culture than did steady-state CD34+ PB cells of normal controls. Single-cell culture studies showed a substantial difference in the number of SCF-responsive or SCF+TPO-responsive mast cell progenitors in CD34+ PB cells between the two groups. In the presence of TPO, CD34+ PB cells from asthmatic children could respond to a suboptimal concentration of SCF to a greater extent, compared with the values obtained by those of normal controls. Six-week cultured mast cells of asthmatic subjects had maturation properties (intracellular histamine content and tryptase/chymase enzymatic activities) similar to those derived from mobilized CD34+ PB cells of nonasthmatic subjects. An increase in a potential of circulating hemopoietic progenitors to differentiate into mast cell lineage may contribute to the recruitment of mast cells toward sites of asthmatic mucosal inflammation.

Involvement of CD27/CD70 interactions in antigen-specific cytotoxic T-lymphocyte (CTL) activity by perforin-mediated cytotoxicity

CD27 molecules are shown to be essential in the regulation of the death, activation and differentiation of T and B cells. However, the influence of CD27 on cytotoxic T‐cell function remains obscure. Autologous EBV transformed B‐cell lines (LCL), which highly express CD27 ligand CD70, here stimulated T cells and induced the cytotoxic T‐lymphocyte (CTL) activity via T‐cell antigen receptors (TCR). The cytotoxicity against LCL was diminished when anti‐CD70 blocking MoAb was added initially in the culture. Resting T cells killed more CD70‐transfected P815 cells than wild type P815 cells in the presence of anti‐CD3 MoAb as measured by a 4‐h 51Cr release assay, and the cytotoxicity of both of the cell populations completely disappeared in the presence of concanamycin A (CMA). The expression of the perforin by the LCL‐induced CTL in the presence of anti‐CD70 blocking MoAb was diminished as compared with that without the blockage of CD27/CD70 interactions. The CTL induced by LCL did not kill Fas‐transfected WR cells. CD27 signalling in the T cells did not affect Fas ligand (FasL) mRNA expression, LAK activity and IFN‐γ synthesis in humans. Our data demonstrate that CD27/CD70 interactions enhance the cytotoxicity of CTL in the induction phase through enhancement of killing activity induced via the perforin‐dependent mechanism, but not via the Fas/FasL system.

Direct B/B–cell interactions in immunoglobulin synthesis

The principal roles of B/B‐cell interactions in immune response have not yet been established. We therefore investigated B/B‐cell interactions in immunoglobulin synthesis via direct cell‐to‐cell contact, particularly in the tumour necrosis factor receptor (TNFR)/tumour necrosis factor (TNF) family. We prepared highly purified peripheral blood B cells and stimulated them with Epstein–Barr virus (EBV)‐transformed B lymphoblastoid cell lines (LCLs) as activated human B cells. The IgG production by B cells was increased by the addition of fixed LCLs in a dose‐dependent manner in the presence of IL‐10 plus IL‐2. LCLs strongly expressed CD40 and CD70 on their surface, but marginal or no CD154, CD27, OX40 (CD134) and CD134 ligand. The enhancement of immunoglobulin production by LCLs was completely blocked by the initial addition of anti‐CD70 blocking MoAb, but not by anti‐CD154 or anti‐CD134 ligand MoAb. The addition of LCLs also caused a reduction in CD27 expression on B cells, and this effect was completely blocked by anti‐CD70 MoAb, indicating a direct B cell–LCL contact via CD27/CD70. LCLs markedly promoted B‐cell differentiation into plasma cells in the presence of IL‐10 plus IL‐2. These findings demonstrate that direct interactions between B and B cells via CD27/CD70 induce immunoglobulin production by promoting the generation of plasma cells.

Presenility of granulocytes in Down syndrome individuals

Neutrophil function defects occur in individuals with Down syndrome (DS). We examined apoptosis of granulocytes (neutrophils and eosinophils) in DS individuals and control healthy subjects. Granulocyte survival was shortened in DS individuals, and the percentage of apoptotic granulocytes from DS during incubation was significantly higher than that from healthy subjects. The difference was time-dependent, and that between DS and healthy subjects was nearly 30% after longer periods of incubation. In control granulocytes, both granulocyte-macrophage colony-stimulating factor (10 ng/ml) and interleukin-5 (5 ng/ml) counteracted the programmed cell death and delayed the apoptosis caused by anti-Fas antibodies, whereas those inflammatory cytokines were not able to completely prevent cellular apoptosis in DS patients. Apoptosis and functional impairment of granulocytes may contribute to the risk of infections underlying pathological conditions of DS, and accelerated apoptosis of granulocytes may be a factor to prevent chronic airway inflammation and bronchial asthma in DS individuals.

Polarization of Th1/Th2 in human CD4^+ T cells separated by CD62L : analysis by transcription factors

Background:  T‐cell surface antigens that differentiate clearly between Th1 and Th2 have not been identified. Discrimination of Th1/Th2 subpopulations by CD62L expression has been reported. We investigated the expression of transcription factors that regulate Th1/Th2 cytokine synthesis in human CD4+ T‐cell subpopulations separated by CD45RO and CD62L, and compared the ratio of CD62L+ to CD62L− cells between healthy individuals and patients with allergic diseases.

Detection of neutrophil-associated immunoglobulin using flow cytometry in autoimmune neutropenia of infancy

Background : 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.

Hematopoietic stem cell transplantation for pulmonary alveolar proteinosis associated with primary immunodeficiency disease

Pulmonary alveolar proteinosis (PAP) is a rare disorder that is characterized by the excessive accumulation of surfactant-like materials in the alveoli, leading to hypoxemic respiratory failure. We describe two Japanese infants with PAP associated with hypogammaglobulinemia and monocytopenia. These patients may have underlying primary immunodeficiency (PID) and were successfully treated with allogeneic hematopoietic stem cell transplantation (HSCT). This report indicates that allogeneic HSCT may provide a curative treatment for PAP associated with PID.