Chi Chang Shieh

Superoxide activates very late antigen-4 on an eosinophil cell line and increases cellular binding to vascular cell adhesion molecule-1.

The recruitment of eosinophils to the airway is a key event in the pathogenesis of allergy. Very late antigen‐4 (VLA‐4), an integrin ligand for vascular cell adhesion molecule‐1 (VCAM‐1), is expressed on eosinophils. VLA‐4‐mediated adhesion of eosinophils to VCAM‐1 may contribute to their selective recruitment to tissues in allergy. Reactive oxygen species (ROS), including nitric oxide (NO), are abundant in the airway of allergic patients, but their role in pathogenesis of allergy is unclear. In this investigation, we studied the effects of ROS on integrin‐mediated eosinophil adhesion. Recombinant soluble VCAM‐1 and ICAM‐1 were used to test the effects of ROS on the integrin‐mediated adhesion of an eosinophil cell line. We used phorbol 12‐myristate 13‐acetate‐stimulated neutrophils and hypoxanthine to generate superoxide, NO donors as sources of NO, and a static cell‐to‐protein adhesion assay to analyze cellular adhesion. Stimulated neutrophils significantly increased eosinophil binding to VCAM‐1, which was reversed in the presence of superoxide dismutase. Neutrophils from a chronic granulomatous disease patient lacked this activity in enhancing eosinophil adhesion. Our results suggest that the balance between ROS molecules in different tissue microenvironments may change the integrin‐mediated leukocyte adhesion and is likely to be a key factor in leukocyte recruitment in allergic inflammation.

Molecular quality control machinery contributes to the leukocyte NADPH oxidase deficiency in chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited immunodeficiency disease caused by defects in leukocyte NADPH oxidase. Various inherited defects in one of the membrane-bound components of NADPH oxidase, gp91-phox, cause X-linked (X91) CGD. Analysis of three patients with X91 CGD revealed that different mechanisms of molecular quality control lead to the common phenotype of absence of mature membrane-bound NADPH oxidase complex in leukocytes. In the first patient, aberrant intron splicing created a premature stop codon. However, the mutant mRNA was degraded prematurely, which prevented the production of truncated protein. In the second patient, a frameshift mutation with the potential to generate a gp91-phox polypeptide, with an aberrant and elongated C-terminus, led to barely detectable levels of gp91-phox, even though the reported functional domains of the protein appeared unaffected. In the third patient, a point mutation created a single amino acid change in the predicted FAD-binding site of gp91-phox. Although gp91-phox was detectable with Western blotting, no cytochrome b(558) was expressed on the cell surface. These analyses showed that molecular quality control machinery plays an important role in the pathogenesis of CGD, not only in the X910 but also in the X91- form of this X-linked disease.

Membrane anchoring of calnexin facilitates its interaction with its targets.

Calnexin, a chaperone that resides in the endoplasmic reticulum, participates in the quality control function of this compartment. Many glycoproteins in the process of folding associate transiently with this chaperone via interactions involving the recognition of their mono-glucosylated glycans. Some misfolded proteins which are retained in the endoplasmic reticulum exhibit prolonged association with calnexin. We have examined whether the transmembrane and cytoplasmic domains of calnexin influence the association of this chaperone with its targets. Interactions of wild type and truncated calnexin with a glycoprotein that is retained in the endoplasmic reticulum (the lymphocyte tyrosine kinase, Ltk), with membrane IgM heavy chains, and with the MHC class I heavy chain protein were investigated. A soluble calnexin molecule lacking the transmembrane domain and cytoplasmic tail does not associate with any of these proteins. When a heterologous transmembrane domain is fused to the lumenal portion of calnexin, this membrane-bound protein can bind Ltk, IgM heavy chains, and MHC class I heavy chain proteins. These results suggest that calnexin must be membrane-anchored in order to recognize its substrates.

Comparison of two specific allergen screening tests in different patient groups

UniCAP and multiple-antigen simultaneous test (MAST) are among the widely used specific allergen tests. The Phadiatop and Fx5 are the multi-allergen UniCAP screening tests for inhalant allergens and common food allergens, respectively. We compared the differences between Phadiatop-Fx5 and MAST as screening allergen tests to clarify the optimal tests for different groups of allergic patients. Serum samples of 224 consecutive allergic patients were tested with Phadiatop, Fx5 and MAST. Results of these allergen tests were compared and analyzed in subgroups categorized by age, serum IgE levels and the clinical departments where the patients were treated. We found that among the 224 patients, 155 patients (69.2%) tested positive with Phadiatop while 137 (61.1%) tested positive with MAST for inhalant allergens. Twenty patients were Phadiatop(+)/MAST(-), while only 2 were Phadiatop(-)/MAST(+). There were 57 patients (25.4%) who tested positive with Fx5, while 32 (14.3%) tested positive with MAST for food allergens. Thirty-eight patients were Fx5(+)/MAST(-), while 13 were Fx5(-)/MAST(+). The disagreement between these two tests was more apparent in food allergen tests than in inhalant allergen tests. Most cases of disagreement occurred in younger age groups and in the patient group with IgE > 500 IU/ml. These results suggested that UniCAP allergen screening tests might be more effective in certain patient groups as screening tests.

Neonatal Solitary Liver Abscess: Report of One Case

We report a case of a solitary liver abscess in a 5-week-old female. She was full term, and there were no predisposing events or immune deficiencies. The only sign of her disease was a gradually distended abdomen. A prior episode of fever with possible occult bacteremia was implicated in the development of her abscess. The abdominal sonography and magnetic resonance image (MRI) did not provide any definite preoperative diagnostic information. Surgical resection of the abscess and a short course of antibiotic therapy cured the disease. This patient was still well following 2 years of check-ups by sonography. The possibility of a pyogenic liver abscess should be considered in the differential diagnosis of neonatal hepatic mass. That is, even if there is not a definite diagnostic focus on finding an infection.