Ken Ohta

Stem cell factor has histamine releasing activity in rat connective tissue-type mast cells

Stem cell factor (SCF) was documented to be involved in the growth of mast cells controlled by fibroblasts. We tested the effect of recombinant rat SCF on degranulation from rat peritoneal mast cells (connective tissue-type mast cells: CTMC). SCF induced histamine release (approximately 20% of total histamine content) in a dose-dependent fashion. The release response was relatively rapid and reached a maximum within 5 min. The release showed total dependence on the presence of extracellular phosphatidylserine (PTS). These results reveal that SCF has histamine releasing activity in CTMC.

Hemopoietic Growth Factors Regulate the Survival of Human Basophils in vitro

Human basophils were purified from normal peripheral blood, using density gradient followed by negative panning selection. We tested the effects of hemopoietic growth factors on the survival of these basophils in vitro. In the absence of exogenous factors, basophils (purity greater than 90%) decreased in number rapidly. At day 7 only 11% of the cells remained alive in cultures; less than 1% of cells survived at day 14. Interleukin (IL)-3 maintained numbers of viable cells; cell viability was 67% at day 7 and 45% at day 14. Granulocyte-macrophage (GM)-colony-stimulating factor (CSF) exhibited slight effect on the survival; 33% of cells remained at day 7. Other growth factors including granulocyte (G)-CSF, macrophage (M)-CSF, and IL-4 had no significant effect on the survival of basophils at all. Morphological and functional characterization of cells maintained by IL-3 revealed that they belonged to the basophil lineage. These observations indicate that normal basophils possess functional receptors for IL-3 and GM-CSF and that both factors modulate immediate- and delayed-type hypersensitivity reactions by prolonging the life span of basophils.

Haemopoietic growth factors induce human basophil migration in vitro

Accumulation of basophils in inflammatory sites is an important aspect of the late‐phase allergic reaction involving skin and upper and lower airways, suggesting the existence of mechanisms for basophil migration. Because haemopoietic growth factors have been shown to stimulate various functions of human basophils, we tested the ability of haemopoietic growth factors to migrate basophils in vitro. Both IL‐3 and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) induced migration of purified normal basophils (purity c. 80%) in a dose‐dependent fashion at picomolar concentrations, while granulocyte (G)‐CSF, macrophage (M)‐CSF, and IL‐4 had no effect at all. Chequerboard analyses indicate that migratory activity of both factors are chemokinetic. These results suggest that local production of both factors during allergic reactions might potentially play an initial role in the recruitment of basophils from the circulation to sites of inflammatory reactions.

Interleukin 6B cell stimulatory factor-II is expressed and released by normal and transformed human bronchial epithelial cells

Airway epithelial cells have a potential to participate in local immune and inflammatory responses via releasing biologically active compounds. We studied the expression and release of interleukin 6 (IL-6), a multifunctional cytokine possibly involved in tissue immune responses. Primary culture of normal human bronchial epithelial cells and its transformed cell line BEAS-2B released significant amount of biologically and immunologically intact IL-6 into media. A protein synthesis inhibitor cycloheximide abolished the IL-6 release, suggesting a de novo synthesis. Northern blot analysis demonstrated the expression of the specific IL-6 mRNA. Human bronchial epithelial cells can produce IL-6 and contribute to the local activity of IL-6, suggesting that these cells may play a role in the regulation of airway immune responses.

IgG1 Antibodies to House Dust Mite (Dermatophagoides farinae) and Late Asthmatic Response

Thirteen asthmatic patients sensitive to mite were challenged by inhalation of an extract of mites (Dermatophagoides farinae). Seven showed dual bronchial reactions and 5 showed isolated immediate responses. No patient showed an isolated late reaction. Six of seven patients with dual reaction had higher IgG1 antibodies than the 5 patients with isolated immediate reaction when examined before the challenge. A similar result was obtained in terms of levels of immune complex. IgE, IgG4 and total IgG antibodies were not predictive for late reaction. These results suggest that there is a close correlation of the presence of high IgG1 antibodies with a propensity to develop late asthmatic responses. The meaning of this observation is discussed.

Studies in atopic asthma with emphasis on correlation among various tests and various antibodies

The prick-test titration, allergen provocation test, acetylcholine inhalation test, total serum IgE measurement, histamine release test, and serum IgE, IgG, IgA, and IgM antibody determinations were carried out in atopic asthmatic patients who had never received immunotherapy with mite extract. Comparison of these procedures shows good correlation between them. Skin-test titration appears to be a fairly accurate and reliable method to determine causative allergens. The antigen inhalation provocation test tends to be positive among subjects with low thresholds to acetylcholine. This indicates that patients with airway tracts hyperreactive to acetylcholine are prone to asthma attacks even with exposure to small amounts of specific allergen and probably to various stimuli. Atopic subjects produce more IgE antibody and other antibodies than nonatopic subjects do. The quantity of specific antibodies to mite was lowest for IgM in atopic subjects.

Human IgE, IgG and IgE Antibody Synthesis in vitro

Human IgE biosynthesis in vitro was studied by co-culturing T and B cells from atopic patients and normal controls in the presence of 10 microliter/ml pokeweed mitogen for 7 days. IgE and anti-mite IgE ab in the culture media significantly correlated with those in plasma. Normal T cells suppressed in vitro production of IgE and IgE ab significantly more than did atopic T cells but no difference was found in IgG production. The culture of B cells alone (T-depleted fraction) produced IgE equally as well as the co-culture of T and B cells. Anti-mite IgE ab was also produced by B cells alone from mite-sensitive patients. However, IgE biosynthesis in vitro was not consistently affected by pokeweed mitogen. The results suggest a deficiency of the T suppressor system in atopy and the existence of T-independent IgE-producing cells.

Human IgE Antibody-Forming Cells

In vitro IgE and antimite IgE antibody (IgE Ab) synthesis was investigated. Peripheral blood lymphocytes (PBL) from atopic patients depleted of E-rosetting T cells developed IgE and IgE Ab in the absence of pokeweed mitogen (PWM), and it was not significantly affected by addition of T cells or of PWM. 1,000 R irradiation decreased more than 50% of the IgE and IgE Ab-producing capacity in 2 of 8 cases, but the remainder were not significantly affected. Increase of the γ-ray dose from 1,000 to 12,000 R did not result in more suppression. Radio-resistant as well as radio-sensitive subpopulations may exist in the PBL of atopic patients, The radio-sensitive component of IgE and IgE Ab formation was suppressed by PWM, while the radio-resistant component was not affected.