Hiroyuki Osuna

Food‐dependent exercise‐induced anaphylaxis: influence of concurrent aspirin administration on skin testing and provocation

Summary Background Provocation tests in patients with food‐dependent exercise‐induced anaphylaxis (FDEIA) are often negative, even after a sufficient quantity of the implicated food and exercise have been taken.

Significance of Carbohydrate Epitopes in a Latex Allergen with β-1,3-Glucanase Activity

Background: One of the latex allergens, Hev b 2, has β-1,3-glucanase activity. The entire sequence of this allergen is already known. There is one potential N-glycosylation site in this molecule (27Asn). Heterogeneous glycosylation of this Asn residue could be a source of the multiplicity of natural Hev b 2. Possible participation of the carbohydrate epitopes of latex β-1,3-glucanase isoenzymes in their IgE-binding capacity and cross-reactivity was investigated in this study. Methods: β-1,3-Glucanase isoenzymes were separated based on their affinities for concanavalin A. IgE-binding capacity and cross-reactivity were examined by immunoblotting and enzyme-linked immunosorbent assay (ELISA). Sequence heterogeneity among the isoenzymes was probed by peptide mass mapping after lysyl endopeptidase digestion. To clarify the relation to Hev b 2, N-terminal sequencing was performed on a fragmented peptide common to the separated isoenzymes. Results: Basic β-1,3-glucanase was subdivided into two glycosylated isoenzymes (GI and GII) and one non-glycosylated isoenzyme (GIII). IgE antibodies in latex-positive sera chiefly recognized the glycosylated isoenzymes. Inhibition ELISA supported the significance of the carbohydrate epitopes for the IgE recognition and cross-reactivity. However, non-glycosylated GIII, as well as GI and GII, produced positive results in a skin prick test. The three β-1,3-glucanase isoenzymes shared a partial sequence in common with Hev b 2. Conclusions: Our results suggest that the carbohydrate epitopes in Hev b 2 homologues are relevant to an in vitro diagnosis of latex allergy and the accompanying cross-reactivity. Carbohydrate epitopes do not necessarily provoke allergic symptoms. Therefore, the actual allergenicity of Hev b 2 and its homologues should be carefully evaluated not only by in vitro IgE tests but also by in vivo tests.

Neuropeptides concentrations in the skin of a murine (NC/Nga mice) model of atopic dermatitis

BACKGROUND It has been reported that the expression of neuropeptides (NPs), and the density and structure of peripheral nerves in atopic dermatitis (AD) are different from those in normal skin. OBJECTIVE We investigated the role of NPs, in the development of AD with quantitative study of substance P (SP) and calcitonin gene-related peptide (CGRP) in the skin of AD-model mice. METHODS We measured the NPs in the skin of mice (NC/Nga as AD-model mice, BALB/c and C57BL/6 as control) by enzyme-linked immunosorbentassay (ELISA). Peripheral nerve fibers and SP in the skin were stained by immunohistochemical staining, using anti-PGP9.5 antibody and anti-SP antibody. RESULTS Under conventional condition, SP concentration in AD-like skin lesions of NC/Nga mice was higher than that in non-affected skin of the same mice. Under specific pathogen-free condition, SP concentration in the skin of NC/Nga mice was higher than that in the skin of BALB/c and C57BL/6 mice. In contrast, CGRP concentration in the skin lesions was lower than that in non-affected skin of NC/Nga mice. SP was detected not only in the nerve fibers in the dermis but also in mast cells in the inflammatory areas. CONCLUSIONS The skin of NC/Nga mice contains more SP congenitally, and environmental factors may aggravate this abnormal condition. We hypothesize that increase of SP accompanied with a decrease of CGRP in the skin may play important roles in the pathogenesis and development of AD.

Late-onset anaphylaxis to fermented soybeans: the first confirmation of food-induced, late-onset anaphylaxis by provocation test

BACKGROUND Late-onset anaphylactic reactions without early-phase reactions are rarely reported. The hypothesized mechanism of late-onset anaphylaxis to fermented soybeans is delayed absorption or release into the bowel rather than an immunologic phenomenon. OBJECTIVES To investigate the mechanisms of late-onset anaphylaxis to fermented soybeans in 2 patients and to characterize the allergens involved in anaphylaxis caused by fermented soybeans. METHODS Two patients underwent skin prick-by-prick tests with fermented soybeans as is. We used an open challenge for the provocation test of anaphylaxis and measured changes in plasma histamine, plasma tryptase, serum eosinophil cationic protein, and plasma leukotriene B4 levels in 1 patient. In addition, specific IgE against fermented soybeans and the allergens of fermented soybeans were detected by enzyme-linked immunosorbent assay and immunoblotting, respectively. RESULTS The results of the prick-by-prick tests with fermented soybeans as is were positive in both patients and negative in control subjects. The challenge with 50 g of fermented soybeans caused generalized urticaria and dyspnea 13 hours after ingestion of fermented soybeans in 1 patient. In addition, his plasma histamine and tryptase levels transiently elevated during the anaphylactic event. In enzyme-linked immunosorbent assay, the patients showed elevated IgE levels to the proteins of fermented soybeans. Serum IgE antibodies of patients 1 and 2 were bound to approximately 5- and 26-kDa proteins in immunoblotting of fermented soybeans, respectively. CONCLUSION To our knowledge, this is the first report of late-onset anaphylaxis provoked by the challenge test half a day after ingestion of fermented soybeans.