Characterization of a novel human mast cell line that responds to stem cell factor and expresses functional FcεRI.

BACKGROUND: Studies of human mast cells (MCs) are constrained by the paucity of functional cell lines, the expense of maintaining MCs in culture, and technical complexities. OBJECTIVE: We derived and characterized a human MC line that arose spontaneously from a culture of nontransformed hematopoietic progenitor cells. METHODS: CD34(+) enriched mononuclear cells derived from a donor with aspirin-exacerbated respiratory disease were cultured for 8 weeks with stem cell factor and IL-6 and with IL-3 for the first week only. The cells (termed LUVA cells) survived and proliferated without further addition of any growth factors and have been maintained in culture for approximately 2 years. RESULTS: LUVA cells possess metachromatic cytoplasmic granules that are immunoreactive for tryptase, cathepsin G, and carboxypeptidase A3. They express transcripts encoding FcεRI, c-kit, chymase, tryptase, histidine decarboxylase, carboxypeptidase A3, and the type 1 receptor for cysteinyl leukotrienes. Flow cytometry confirmed uniform expression of FcεRI, c-kit, and FcγRII. FcεRI cross-linkage induced the release of ß-hexosaminidase, prostaglandin D(2), thromboxane A(2), and macrophage inflammatory protein 1ß. Immortalization was not associated with either a known genomic mutation of c-kit in the donor or a somatic mutation of c-kit within the cells, and it was not associated with c-kit autophosphorylation. CONCLUSIONS: LUVA cells are an immortalized human MC line that can be maintained without stem cell factor and display high levels of normally signaling c-kit and FcεRI. These cells will prove valuable for functional human MC studies.

Lack of a role for cross-reacting anti-thyroid antibodies in chronic idiopathic urticaria.

The etiology of chronic idiopathic urticaria (CIU) is attributed to autoantibodies directed against the alpha-chain of the high-affinity IgE receptor (FcepsilonRIalpha) or IgE on mast cells in 30-60% of patients. Approximately 30% of CIU patients have Hashimoto's thyroiditis (HT). We investigated the pathophysiologic relationship of anti-thyroid and anti-FcepsilonRIalpha antibodies. Nine individuals with both CIU and HT underwent autologous serum skin testing (ASST) and sera were assayed for thyroid autoantibodies, thyroid-stimulating hormone, and anti-FcepsilonRIalpha antibodies. Serum samples were studied for their ability to activate a human mast cell line (LUVA) as determined by cysteinyl leukotriene (CysLT) production. Experiments were performed to determine whether epitope cross-reactivity could explain the high incidence of HT found in CIU patients. A significant proportion of CIU patients had a positive ASST (nine of six) and anti-FcepsilonRIalpha antibodies (six of nine). Incubation of patient sera with FcepsilonRIalpha, but not thyroglobulin or thyroid peroxidase, resulted in the decreased ability to detect anti-FcepsilonRIalpha antibodies. Incubation with thyroid antigens did not inhibit CysLT production by mast cells. Epitopic cross-reactivity does not explain the increased prevalence of HT found in CIU patients. The frequent concurrence of HT and CIU likely reflects a genetic tendency toward autoimmune diseases.

Impact of preinterventional arterial remodeling on neointimal hyperplasia after implantation of (non-polymer-encapsulated) paclitaxel-coated stents: a serial volumetric intravascular ultrasound analysis from the ASian Paclitaxel-Eluting Stent Clinical Trial (ASPECT).

BACKGROUND: This study used serial volumetric intravascular ultrasound (IVUS) to evaluate the effect of preinterventional arterial remodeling on in-stent intimal hyperplasia (IH) after implantation of non-polymer-encapsulated paclitaxel-coated stents. METHODS AND RESULTS: Patients were randomized to placebo or one of two doses of paclitaxel (low dose, 1.28 microg/mm2; high dose, 3.10 microg/mm2). Complete preinterventional, post-stent implantation, and follow-up IVUS were available in 18 low-dose and 21 high-dose patients. IH volumes were similar in low-dose and high-dose patients: 17.6+/-15.1 mm3 in low-dose patients and 13.1+/-13.3 mm3 in high-dose patients (P=0.3). Therefore, IVUS findings in low- and high-dose patients were combined. Preinterventional remodeling was assessed by comparing lesion site to proximal and distal reference arterial area: positive remodeling (lesion>proximal reference, n=13), intermediate remodeling (distal reference