[A CASE OF A GIRL WITH ANAPHYLAXIS INDUCED BY INHALATION OF SOYBEAN DUST].

The patient was a 3-year-old girl whose father was employed sorting and washing soybeans. She exhibited transient respiratory distress and loss of activity on the same day or the next day after her father came home wearing work clothes with soybean dust on them. One day, she developed anaphylaxis after being lifted into her father's arms while he was wearing his work clothes. Although a blood test was positive for soybean and Gly m 4-specific IgE antibodies, the girl was able to consume soy products (not including soy milk, which she had never consumed) without any issues. The father was instructed to change clothes before leaving work and bathe immediately upon returning home, and the girl has not had any further episodes of respiratory distress, loss of activity, or anaphylaxis. Though reports of anaphylaxis from soybean antigen inhalation are extremely rare, it is very likely that inhalation of soybean dust from the father's work clothes induced anaphylaxis in this case.

Phospholipase D2: a pivotal player modulating RBL-2H3 mast cell structure.

The current study examined the role of PLD2 in the maintenance of mast cell structure. Phospholipase D (PLD) catalyzes hydrolysis of phosphatidylcholine to produce choline and phosphatidic acid (PA). PLD has two isoforms, PLD1 and PLD2, which vary in expression and localization depending on the cell type. The mast cell line RBL-2H3 was transfected to overexpress catalytically active (PLD2CA) and inactive (PLD2CI) forms of PLD2. The results of this study show that PLD2CI cells have a distinct star-shaped morphology, whereas PLD2CA and RBL-2H3 cells are spindle shaped. In PLD2CI cells, the Golgi complex was also disorganized with dilated cisternae, and more Golgi-associated vesicles were present as compared with the PLD2CA and RBL-2H3 cells. Treatment with exogenous PA led to the restoration of the wild-type Golgi complex phenotype in PLD2CI cells. Conversely, treatment of RBL-2H3 and PLD2CA cells with 1% 1-Butanol led to a disruption of the Golgi complex. The distribution of acidic compartments, including secretory granules and lysosomes, was also modified in PLD2CI cells, where they concentrated in the perinuclear region. These results suggest that the PA produced by PLD2 plays an important role in regulating cell morphology in mast cells.

TOM1L1 is a Lyn substrate involved in FcepsilonRI signaling in mast cells.

Protein-tyrosine kinase Lyn and Syk are critical for antigen-receptor-induced signal transduction in mast cells. To identify novel Lyn/Syk substrates, we screened an RBL-2H3 bacterial expression library for proteins that were tyrosine phosphorylated with baculoviral expressed Lyn or Syk. Five clones as potential Lyn substrates and eight clones as Syk substrates were identified including known substrates such as SLP-76, LAT, and alpha-tubulin. A potential substrate of Lyn identified was the molecule TOM1L1, which has several domains thought to be important for membrane trafficking and protein-protein interactions. Because the function of TOM1L1 is unclear, the rat TOM1L1 full-length cDNA was isolated and used to express the protein in COS-1 and RBL-2H3 mast cells. In COS-1 cells, the co-transfection of TOM1L1 and Lyn, but not Syk, resulted in the tyrosine phosphorylation of TOM1L1. In RBL-2H3 mast cells, the overexpressed TOM1L1 was strongly tyrosine phosphorylated in non-stimulated cells, and this phosphorylation was enhanced by FcepsilonRI aggregation. By subcellular fractionation, wild-type TOM1L1 was mainly in the cytoplasm with a small fraction constitutively associated with the membrane; this association was markedly reduced in deletion mutants lacking several of the protein interaction domains. The overexpression of TOM1L1 enhanced antigen-induced tumor necrosis factor (TNF) alpha generation and release. Both protein interaction domains (VHS and the coiled-coil domains) were required for the increased TNFalpha release, but not the increased TNFalpha generation. These results suggest that TOM1L1 is a novel protein involved in the FcepsilonRI signal transduction for the generation of cytokines.

Squamous cell carcinoma-related antigen in children with acute asthma.

BACKGROUND: Increased serum levels of squamous cell carcinoma-related antigen (SCCA) have been observed in patients with allergic disorders, such as atopic dermatitis and bronchial asthma. T(H)2 cytokines, which are known to be involved in the pathogenesis of allergic disorders, stimulate new synthesis of SCCA in cultured human airway epithelial cells. OBJECTIVE: To investigate whether SCCA levels increase during acute exacerbations of asthma in children and whether the T(H)2 cytokines, interleukin 4 (IL-4) and IL-13, are associated with SCCA levels. METHODS: Serum levels of SCCA, IL-4, and IL-13 were measured by enzyme immunoassay during the acute phase of an asthma exacerbation (on hospital admission) and in the recovery phase (after symptoms had subsided). RESULTS: In the 35 children who participated in this study, serum levels of SCCA were significantly elevated in the acute phase (mean +/- SD, 3.09 +/- 2.03 ng/mL) compared with the recovery phase (mean +/- SD, 1.47 +/- 0.64 ng/mL) of an asthma exacerbation (P < .001). In 12 children, the IL-13 levels were observed to correlate with SCCA levels during the recovery phase (r = 0.68, P = .02) but not during the acute phase of an asthma exacerbation. CONCLUSIONS: Serum SCCA levels increase during the acute phase of an asthma exacerbation. During this phase, the increased synthesis of SCCA is not associated with IL-13 but rather mediated by other undefined stimuli. IL-13 may contribute to the basal production of SCCA in asthmatic children.

Phospholipase D1 regulates high-affinity IgE receptor-induced mast cell degranulation.

To investigate the role of phospholipase D (PLD) in FcepsilonRI signaling, the wild-type or the catalytically inactive forms of PLD1 or PLD2 were stably overexpressed in RBL-2H3 mast cells. FcepsilonRI stimulation resulted in the activation of both PLD1 and PLD2. However, PLD1 was the source of most of the receptor-induced PLD activity. There was enhanced FcepsilonRI-induced degranulation only in cells that overexpressed the catalytically inactive PLD1. This dominant-negative PLD1 enhanced FcepsilonRI-induced tyrosine phosphorylations of early signaling molecules such as the receptor subunits, Syk and phospholipase C-gamma which resulted in faster release of Ca(2+) from intracellular sources. Therefore, PLD1 negatively regulates signals upstream of the Ca(2+) response. However, FcepsilonRI-induced PLD activation required Syk and was downstream of the Ca(2+)response, suggesting that basal PLD1 activity rather than that activated by cell stimulation controlled these early signaling events. Dominant-negative PLD1 reduced the basal phosphatidic acid formation in unstimulated cells, which was accompanied by an increase in FcepsilonRI within the lipid rafts. These results indicate that constitutive basal PLD1 activity by regulating phosphatidic acid formation controls the early signals initiated by FcepsilonRI aggregation that lead to mast cell degranulation.

Dual regulation of phospholipase D1 by protein kinase C alpha in vivo.

The regulation of phospholipase D1 (PLD1), which has been shown to be activated by protein kinase C (PKC) alpha, was investigated in the human melanoma cell lines. In G361 cell line, which lacks PKCalpha, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced PLD activation was potentiated by introducing PKCalpha by the adenovirus vector. The kinase-negative PKCalpha elevated TPA-induced PLD activity less significantly than the wild type. A PKC specific inhibitor GF109203X lowered PLD activation in the cells expressing PKCalpha, but did not prevent PLD potentiation induced by the kinase-negative PKCalpha. Expression of PKCbetaII and the kinase-negative PKCbetaII enhanced TPA-stimulated PLD activity moderately in MeWo cell line, in which PKCbetaII is absent. Furthermore, the TPA treatment increased the association of PKCalpha, PKCbetaII, and their kinase-negative mutants with PLD1 in melanoma cells. These results indicate that PLD1 is dually regulated through phosphorylation as well as through the protein-protein interaction by PKCalpha, and probably by PKCbetaII, in vivo.