Tsukako Kameyama

The role of T lymphocytes in patients with food-sensitive atopic dermatitis

The role of T lymphocytes was assessed in patients with food-sensitive atopic dermatitis (AD). T lymphocytes plus monocytes responded well to ovalbumin or bovine serum albumin (BSA) in children with AD who were sensitive to hens egg or cows milk compared with healthy children and children with immediate allergic symptoms who are sensitive to hens egg or cows milk. The responding cells were shown to be predominantly CD4+ T lymphocytes. Interleukin-2 activity and interferon-gamma concentrations in culture supernatants of ovalbumin-stimulated peripheral blood mononuclear cells (PBMCs) from patients with AD who were sensitive to hens egg were significantly higher than those of healthy children and patients sensitive to hens egg with immediate symptoms. Expression of Fc epsilon R II on B lymphocytes in cultures of ovalbumin-stimulated PBMCs from patients with AD was significantly higher than that of healthy children, but it tended to be lower than that of patients with immediate symptoms. These results suggest that, in patients with AD who are food sensitive, CD4+ T lymphocytes stimulated by food antigens secrete lymphokines such as interleukin-2 and interferon-gamma that are secreted from TH1 clones in mice, and express Fc epsilon R II on B lymphocyte that is induced by interleukin-4 secreted from TH2 clones in mice. Taken together, cell-mediated immunity may also occur in addition to IgE-mediated hypersensitivity in patients with food-sensitive AD.

Suppression of immunoglobulin production of lymphocytes by intravenous immunoglobulin

The proliferative responses and the immunoglobulin production of peripheral blood mononuclear cells to pokeweed mitogen were dose-dependently suppressed by sulfonated intravenous immunoglobulin (IVIG), polyethylene glycol-treated IVIG, pH 4-treated IVIG, or human γ-globulin, but they were not or only slightly suppressed by human serum albumin or pepsin-treated IVIG. Moreover, the suppression of immunoglobulin production by sulfonated IVIG, polyethylene glycol-treated IVIG, or pH 4-treated IVIG was seen in the cases in which B cells preincubated with IVIGs were cocultured with T cells and monocytes preincubated with or without IVIGs and in the cases in which monocytes preincubated with IVIGs were cocultured with T cells and B cells preincubated with or without IVIGs. However, in the cases in which only T cells were preincubated with IVIGs, immunoglobulin production was not suppressed. The suppression of the monocyte function by IVIGs tended to be less than the suppression of the B-cell function by IVIGs. Moreover, the suppression by IVIGs was blocked by antihuman IgG Fc. Our results suggest that IVIGs suppress the immunoglobulin production of lymphocytes through suppression of the B-cell function and the antigen presenting-cell function by attachment of IVIGs to Fc receptors of B-cell membranes and antigen presenting-cell membranes.

Intravenous Immunoglobulins Suppress Immunoglobulin Productions by Suppressing Ca2+ ‐Dependent Signal Transduction Through Fc γ Receptors in B Lymphocytes

A high dose intravenous immunoglobulin (IVIG) therapy is used in the treatment of a wide range of autoimmune disorders. However, the mechanisms of the action of IVIGs remain poorly understood. To analyse the mechanisms of effects of IVIGs on immunoglobulin (Ig) production of B cells, the effects of IVIGs on B lymphoblastoid cell lines transformed by Epstein‐Barr virus (LCLs) were investigated. The productions of IgG or IgM of LCLs were dose‐dependently suppressed by polyethylene glycol (PEG)‐treated IVIG or pH 4‐treated 1VIG though the productions were not or only slightly suppressed by pepsin‐treated IVIG. The suppression by IVIGs was blocked by anti‐human IgG Fc or anti‐Fc γ RII. C μ gene expression and μ s C terminal gene expression of LCLs were suppressed by PEG‐treated IVIG, whereas neither C μ gene expression nor μ s C terminal gene expression of LCLs were suppressed by pepsin‐treated IVIG. Although the increase in intracellular calcium concentration in LCLs was not suppressed by pepsin‐treated IVIG, the increase was suppressed by PEG‐treated IVIG. This suppressing effect of PEG‐treated IVIG on intracellular calcium concentration of LCLs was blocked by anti‐human IgG Fc or anti‐ Fc γ RII. Our results suggest that IVIGs suppressed the Ca2+ ‐dependent signal transduction through Fc γ R on B‐cell membrane, consequently, the transcription of C γ mRNA, especially secreted γ mRNA was suppressed in the B cells.

Reduced secreted μ mRNA synthesis in selective IgM deficiency of Bloom's syndrome

Serum IgM concentrations were low although serum IgG and IgA concentrations were normal in both our patients with Blooms syndrome. Although the percentages of surface Ig‐earing cells were not reduced, the numbers of Ig‐ecreting cells were markedly reduced. The membran‐ound μ(μm) and secreted μ (μs) mRN As arc produced from transcripts of a single immunoglobulin μ gene by alternative RNA processing pathways. The control of μs mRNA synthesis depends on the addition of poly(A) to μs ‐erminal segment. In both patients, μ mRNA was well detected but μs ‐erminal mRNA was scarcely detected, suggesting that μ mRNA was well transcribed but μs mRNA was not. There was, at least, no mutation or deletion in the μs ‐erminal coding sequence, the RNA splice site (GG/TAAAC) at the 5’ end of μs ‐erminal segment and the AATAAA poly(A) signal sequence in both patients. Our results suggest that selective IgM deficiency in Blooms syndrome is due to an abnormality in the maturation of surface Ig‐earing B cells into Ig‐ecreting cells and a failure of μs mRNA synthesis. Moreover, reduced μs mRNA synthesis may be due to the defect on developmental regulation of the site at which poly(A) is added to transcripts of the μ gene.

Defective Calcium-Dependent Signal Transduction in T Lymphocytes of Ataxia-Telangiectasia

T‐cell functions of two patients with ataxia‐telangiectasia were investigated. Patients with ataxia‐telangiectasia had reduced percentages of circulating CD3+ cells and CD4+ cells, although neither patient had a reduced percentage of circulating CD8+ cells. The proliferative responses and interleukin‐2 production of peripheral blood mononuclear cells to T‐cell mitogens were reduced in the patients. The intracellular calcium concentration in T cells or CD4+ cells from both patients was only slightly increased after phytohaemagglutinin stimulation. Moreover, the concentration after OKT3 stimulation was not or only slightly increased in T cells or CD4+ cells from both patients. Our results suggest that the functional defect of T cells is caused by defective Ca2+‐dependent signal transduction through the CD3 complex of the surface in T cells of ataxia‐telangiectasia.

Improvement of food‐sensitive atopic dermatitis accompanied by reduced lymphocyte responses to food antigen following natural measles virus infection

Five patients with atopic dermatitis (AD) who were sensitive to hens egg were observed before and after natural measles virus infection. Within 4 weeks of natural measles virus infection, the eczematous lesions clearly improved in four of the five patients in whom neither offending foods were eliminated, nor anti‐allergic drugs, systemic steroids and steroid ointment administered. This was accompanied by reduced proliferative responses of peripheral blood mononuclear cells (PBMCs) to ovalbumin (OA). Another patient showed a transient improvement of AD symptoms, from severe to mild, and thereafter returned to severe accompanied by increased proliferative responses of PBMCs to OA. Radioallergosorbent test (RAST) scores for hens egg in all five patients did not change in each level in each patient, except the transiently decreased RAST scores for hens egg in one patient, after the infection. Thus, in patients with AD who are sensitive to food, the improvement of AD symptoms that appeared within 4 weeks of natural measles virus infection was related to reduced proliferative responses of PBMCs to the food antigen following the infection.

Inhibition of proliferative responses of lymphocytes to food antigens by an anti-allergic drug, N(3′,4′-dimethoxycinnamoyl) anthranilic acid (Tranilast) in children with atopic dermatitis

Experimental studies have shown that N(3′, 4′‐dimethoxycinnamoyl) anthranilic acid (Tranilast) inhibits reaginic antibody‐mediated hypersensitivity reactions, and it has been demonstrated to be an effective drug for patients with bronchial asthma. On the other hand, from the nature of the cellular infiltrate seen in eczematous lesions, it appears that some form of cell‐mediated immunity may be involved in addition to IgE‐mediated immunity in the pathogenesis of atopic dermatitis (AD). Moreover, we have previously reported that the proliferative responses of peripheral blood mononuclear cells (PBMCs) to ovalbumin (OA) or bovine serum albumin (BSA) in children with AD who are sensitive to hens egg or cows milk were significantly higher than those of healthy children and hens egg or cows milk sensitive children with immediate symptoms.

Suppression of Proliferative Responses of Lymphocytes to Food Antigens by an Anti-Allergic Drug, Ketotifen Fumarate, in Patients with Food-Sensitive Atopic Dermatitis

Experimental studies have shown that ketotifen fumarate inhibits reaginic antibody-mediated hypersensitivity reactions. In this study, the proliferative responses of peripheral blood mononuclear cells (PBMCs) to ovalbumin (OA) in children with atopic dermatitis (AD), who are sensitive to hens egg, were significantly higher than those of healthy children. The proliferative responses of PBMCs to OA were dose-dependently inhibited by ketotifen in patients with hens egg-sensitive AD. Moreover, the inhibition resulted from the effects of ketotifen on T cells. In contrast, the proliferative responses of PBMCs to phytohemagglutinin and tetanus toxoid were not inhibited by ketotifen. These results suggest that ketotifen inhibits food antigen-specific proliferative responses of PBMCs in patients with food-sensitive AD.

Failure of IgG production due to a defect in the opening of the chromatin structure of Iγ1 region in a patient with IgG and IgA deficiency

Patients with common variable immunodeficiency (CVID) display reduced levels of two or all three of the major immunoglobulin isotypes, and the deficiency is characterized by failure of B cells to differentiate into plasma cells in many cases. A patient (14 years old, female) showed normal serum IgM levels and low serum IgG and IgA levels, including low levels of all IgG subclasses. Northern blot analysis suggested that the patients B cells may be defective at the immunoglobulin heavy chain isotype switch. The germ‐line Cγ1 transcript was amplified from cDNA of healthy controls by the addition of recombinant IL‐2 (rIL‐2) to pokeweed mitogen‐stimulated peripheral mononuclear cells or Staphylococcus aureus Cowan I (SAC)‐stimulated IgM‐producing lymphoblastoid cell lines (LCL) transformed by Epstein‐Barr virus, while it was not amplified from cDNA of the patient. In the Iγ1 region of LCL cultured with SAC plus rIL‐2, the inner cytosine in the 5′C‐C‐G‐G 3′sequence nearest the 3′site of the Iγ1 region, at least, was not completely unmethylated in the patient. Moreover, the DNase I hypersensitive site was not induced in the patients LCL by SAC plus rIL‐2. These results indicate that the defects of the immunoglobulin heavy chain isotype switch in the patients B cells are due to failure in the synthesis of germ‐line Cγ transcripts, and this may be caused by defects in opening of the chromatin structures of specific switch regions.