Kenji Katamura

Autoimmune-related pancreatitis is associated with autoantibodies and a Th1/Th2-type cellular immune response

BACKGROUND & AIMS Although autoimmunity may be involved in some cases of pancreatitis, the mechanism is still unknown. To clarify this, we studied serum autoantibodies, subsets of lymphocytes, and the Th1/Th2 balance of cellular immune responses in patients with autoimmune-related pancreatitis (AIP). METHODS Seventeen patients with AIP (8 men and 9 women; age, 53.2 +/- 13.0 years) were studied. Autoantibodies including antilactoferrin (ALF) or carbonic anhydrase II antibody (ACA-II) were examined using the enzyme-linked immunosorbent assay (ELISA) or the indirect fluorescein antibody method. Intracellular cytokines (interferon gamma and interleukin 4) and subtypes of peripheral blood lymphocytes were examined by flow cytometry and ELISA. RESULTS More than one autoantibody was observed in all 17 patients. Serum antinuclear antibody was detected in 13 of 17 patients, ALF antibody in 13, ACA-II antibody in 10, rheumatoid factor in 5, and anti-smooth muscle antibody in 3, but antimitochondrial antibody in none. The serum levels of ACA-II and LF antibody were not correlated. HLA-DR(+)CD8(+) and HLA-DR(+)CD4(+) cells were significantly increased in peripheral blood (P < 0.05). CD4(+) cells producing interferon gamma and the secreted levels were significantly increased compared with those in controls (P < 0.05), but interleukin 4 was not increased. CONCLUSIONS An autoimmune mechanism against CA-II or LF, and Th1-type immune response, may be involved in AIP.

Early sensitization to house dust mite is a major risk factor for subsequent development of bronchial asthma in Japanese infants with atopic dermatitis: results of a 4-year followup study

BACKGROUND Bronchial asthma (BA) often develops in children with atopic dermatitis (AD). Identification of factors that could predict the development of asthma in children with AD is useful for early intervention. OBJECTIVE We undertook a 4-year followup study to clarify the factors involved in the development of BA in infants with AD. METHODS We registered 169 infants with AD who were free of BA at registration and examined the prevalence and characteristics of the subsequent development of BA among these patients. RESULTS Among the patients followed for 4 years, approximately 45% experienced asthma-like respiratory symptoms, and 35% were diagnosed as asthmatic patients by pediatric allergologists. Patients who developed BA showed early appearance of house dust mite (HDM)-specific immunoglobulin E (IgE) and persistently high levels of food-specific IgE. Male sex, a positive family history of BA, and the appearance of HDM-specific IgE were identified as significant risk factors for the early development of BA, but the significance of these parameters decreased thereafter. A positive family history of AD, the outcome of skin lesions, and keeping furred pets were also identified as risk factors in a part of the followup period. Among the parameters examined, the early appearance of HDM-specific IgE was the most significant risk factor. CONCLUSION Appearance of HDM-specific IgE antibodies in early childhood, which seems to be mainly influenced by genetic factors, is a major risk factor for the subsequent development of BA in children with AD, but the influence decreases after longer followup.

IL-7 induces proliferation, variable cytokine-producing ability and IL-2 responsiveness in naive CD4+ T-cells from human cord blood

We investigated the effects of IL-7 on the proliferation and acquisition of cytokine-producing ability of naive CD4+ T-cells from human cord blood. Naive CD4+CD45RA+ T-cells from human cord blood expressed CDw127 (IL-7R) at higher levels than adult CD4+ CD45RA+ T-cells and produced IL-2 and a small amount of IFN-gamma upon stimulation with PMA and ionomycin. IL-7 induced IL-2-independent proliferation and both Th1- and Th2-type cytokine-producing abilities in cord blood CD4+CD45RA+ T-cells without stimulation via TCR. These results suggest that this IL-7-induced antigen-independent activation mechanism could contribute to maintaining the clonal size of naive T-cells with the potential to differentiate into either Th1 or Th2 cells at the sites of IL-7-expression.

Differential Requirement for the CD40-CD154 Costimulatory Pathway during Th Cell Priming by CD8α+ and CD8α− Murine Dendritic Cell Subsets

Dendritic cells (DCs) regulate the development of distinct Th populations and thereby provoke appropriate immune responses to various kinds of Ags. In the present work, we investigated the role CD40-CD154 interactions play during the process of Th cell priming by CD8α+ and CD8α− murine DC subsets, which have been reported to differently regulate the Th response. Adoptive transfer of Ag-pulsed CD8α+ DCs induced a Th1 response and the production of IgG2a Abs, whereas transfer of CD8α− DCs induced Th2 cells and IgE Abs in vivo. Induction of distinct Th populations by each DC subset was also confirmed in vitro. Although interruption of CD80/CD86-CD28 interactions inhibited Th cell priming by both DC subsets, disruption of CD40-CD154 interactions only inhibited the induction of the Th1 response by CD8α+ DCs in vivo. CD40-CD154 interactions were not required for the proliferation of Ag-specific naive Th cells stimulated by either DC subset, but were indispensable in the production of IL-12 from CD8α+ DCs and their induction of Th1 cells in vitro. Taken together, in our immunization model of Ag-pulsed DC transfer, CD40-CD154 interactions play an important role in the development of CD8α+ DC-driven Th1 responses but not CD8α− DC-driven Th2 responses to protein Ags.

Existence of activated and memory CD4+ T cells in peripheral blood and their skin infiltration in CD8 deficiency.

CD8 deficiency is a rare primary immunodeficiency caused by the defect of a tyrosine kinase, ZAP‐70, which transduces signals from the T cell receptor. We report here a case of CD8 deficiency, having CD4+ T cells with a unique phenotype. The patients T cells did not respond to anti‐CD3 stimulation in vitro, suggesting that they were naive. However, many CD4+ T cells with activated and memory phenotypes, which expressed CD45RO+, HLA‐DR+ and CD25+, were present in the peripheral blood, and these cells accumulated in the perivascular area of his infiltrative erythematous skin lesions. The patients T cells could be activated by a high concentration of phytohaemagglutinin (PHA), indicating the presence of an alternate signalling pathway which bypasses ZAP‐70 and activates CD4+ T cells in vivo. The origin and role of activated CD4+ T cells in the pathogenesis involved in the skin lesions are discussed.

Serum levels of interleukin 4 and soluble CD23 in children with allergic disorders

In order to clarify the clinical significance of serum interleukin 4 (IL-4) levels, we measured serum IL-4 concentrations in allergic and non-allergic children using a highly sensitive sandwich ELISA. The limit of detection of the assay was 0.15 pg/ml in serum samples. Serum IL-4 was detected in 96.3% (53/55) of non-allergic controls, in 92.9% (183/197) of allergic children, in 70% (7/10) of cord blood samples and in 86.7% (26/30) of neonates. The IL-4 levels in sera from non-allergic controls were relatively constant during the ages examined and all samples were under 1.5 pg/ml. In allergic children, the serum levels of IL-4 were significantly elevated, particularly at age 13-24 months. The serum levels of IL-4 did not differ in children with different clinical manifestations of allergy, such as bronchial asthma, and atopic dermatitis. The serum level of soluble CD23 (sCD23) showed an age-dependent change in allergic and non-allergic children and was significantly higher in allergic than in non-allergic infants aged 7 to 12 months, but not in other age groups. There was no significant correlation among serum levels of IL-4, sCD23 and IgE.

Selective Induction of lnterleukin-4- and Interferon-γ-Producing T Cells from Cord Blood Naive T Cells

We investigated the effect of costimulation through CD28 and CD11a on the differentiation of human naive CD4+ T cells with restricted cytokine production profiles. Interleukin (IL)-4 and interferon-γ (IFN-γ) were measured by ELISA and IL-2 was detected by a bioassay. Naive CD4+ T cells proliferated and produced IL-2 upon cross-linking of CD3, and costimulation through CD28 enhanced IL-2 production. After repeated stimulation, CD4+ T cells which were stimulated in the absence of costimulation through CD28 lost their ability to secrete IL-2 and started secreting IL-4 and IFN-γ. Instead in the presence of costimulation through CD28, they secreted IL-2, IL-4 and IFN-γ. Blocking of endogenous IL-4 activity with anti-IL-4 Ab suppressed the IL-4 secretion and prolifeation of T cells.

Limited Ability of Antigen-Specific Th1 Responses to Inhibit Th2 Cell Development In Vivo

Th1 and Th2 cells mutually antagonize each other’s differentiation. Consequently, allergen-specific Th1 cells are believed to be able to suppress the development of Th2 cells and to prevent the development of atopic disorders. To determine whether a pre-existing Ag-specific Th1 response can affect the development of Th2 cells in vivo, we used an immunization model of Ag-pulsed murine dendritic cell (DC) transfer to induce distinct Th responses. When transferred into naive mice, Ag-pulsed CD8α+ DCs induced a Th1 response and the production of IgG2a, whereas CD8α− DCs primed a Th2 response and the production of IgE. In the presence of a pre-existing Ag-specific Th2 environment due to Ag-pulsed CD8α− DC transfer, CD8α+ DCs failed to prime Th1 cells. In contrast, CD8α− DCs could prime a Th2 response in the presence of a pre-existing Ag-specific Th1 environment. Moreover, exogenous IL-4 abolished the Th1-inducing potential of CD8α+ DCs in vitro, but the addition of IFN-γ did not effectively inhibit the potential of CD8α− DCs to prime IL-4-producing cells. Thus, Th1 and Th2 cells differ in their potential to inhibit the development of the other. This suggests that the early induction of allergen-specific Th1 cells before allergy sensitization will not prevent the development of atopic disorders.

ZAP-70 is required for calcium mobilization but is dispensable for mitogen-activated protein kinase (MAPK) superfamily activation induced via CD2 in human T cells

Stimulation with specific pairs of anti‐CD2 antibodies can induce T cell activation and proliferation. In this study, we investigate the significance of ZAP‐70 in CD2 signaling using ZAP‐70‐deficient T cells derived from a CD8‐deficient patient and show that ZAP‐70 is necessary for cellular proliferation and cytokine production in T cells stimulated via CD2. Biochemical analyses show that CD2 stimulation induces activation of mitogen‐activated protein kinase (MAPK) superfamily in ZAP‐70‐deficient T cells, indicating that a ZAP‐70‐independent pathway(s) exists for MAPK superfamily activation via CD2. In contrast, intracellular Ca2+ mobilization and activation of nuclear factor of activated T cells (NFAT) upon CD2 triggering were impaired in T cells lacking ZAP‐70. Furthermore, we found that pharmacological Ca2+ elevation combined with CD2 stimulation restored NFAT activation and subsequent cytokine production in ZAP‐70‐deficient T cells. These results indicate that in CD2 signaling, ZAP‐70 plays an essential role in Ca2+ mobilization and NFAT activation.

Cyclosporin A and FK506 block the negative signaling mediated by surface IgM cross-linking in normal human mature B cells.

Cross-linking of surface IgM (sIgM) or sIgD by anti-IgM Ab or anti-IgD Ab, respectively, induced DNA synthesis in peripheral blood B cells (PBL-B). Cell division, determined by the increase in the number of M phase cells, was also induced when PBL-B were stimulated with anti-IgD Ab plus IL-4 or Staphylococcus aureus Cowan I (SAC), but far less by stimulation with anti-IgM Ab plus IL-4. Anti-IgM Ab did not suppress the DNA synthesis induced by SAC or anti-IgD Ab plus IL-4, but it did suppress the cell division induced by them. Thus, sIgM cross-linking generates both positive and negative signaling to B-cell proliferation. Cyclosporin A (CSA) and FK506 suppressed DNA synthesis and cell division at relatively high concentrations. On the other hand, CSA and FK506 at lower concentrations blocked the anti-IgM Ab-generated inhibition of cell division without affecting DNA synthesis. Low concentrations of CSA did not affect the cell division induced by anti-IgD Ab plus IL-4 but did increase the cell division induced by SAC or anti-IgM Ab plus IL-4, suggesting that stimulation with SAC, as well as with anti-IgM Ab plus IL-4, generates both positive and negative signals to cell division, whereas sIgD lacks the ability to transduce negative signaling.