Biomedical subjects

Sarbjit S Saini

Publications and source records attributed to Sarbjit S Saini.

7 recordsLinked to original sources

PubMed2006

Basophil FcepsilonRI histamine release parallels expression of Src-homology 2-containing inositol phosphatases in chronic idiopathic urticaria.

BACKGROUND: Basophils are implicated in the pathogenesis of chronic idiopathic urticaria (CIU). Autoantibodies to the IgE receptor (FcepsilonRI) and serum histamine releasing activity have been detected in some subjects with CIU, although their role in vivo is unclear. Basophils of patients with CIU have altered FcepsilonRI-mediated histamine release (HR); however, the mechanism is unknown. In the basophil FcepsilonRI signaling pathway, protein levels of Src-homology 2-containing-5'-inositol phosphatase (SHIP)-1 are inversely correlated with the release of mediators or releasability. A related phosphatase, SHIP-2, is a negative regulator of monocyte IgG receptor (FcgammaR) signaling . We hypothesized that SHIP levels are altered in CIU basophils. METHODS: Blood basophils were isolated from cold urticaria, CIU, or normal donors, and FcepsilonRI-dependent and independent HR were quantified. Protein levels of SHIP-1, SHIP-2, spleen tyrosine kinase, and phosphorylated Akt were determined by Western blotting. Subjects' serum was tested for serum histamine releasing activity and anti-FcepsilonRIalpha antibodies. RESULTS: CIU basophils displayed a bimodal response to anti-IgE activation. One half of CIU subjects' basophils had reductions in anti-IgE-induced HR and were designated nonresponders (CIU NR). CIU NR basophil HR remained diminished at 10-fold to 30-fold higher doses of anti-IgE. CIU anti-IgE responder basophils had HR similar to normal subjects. SHIP-1 and SHIP-2 proteins were increased in CIU NR basophils and were linked to reduced phosphoAkt after anti-IgE stimulation. CIU basophil anti-IgE response was not related to the presence of serologic factors. CONCLUSION: In CIU basophils, the observed changes in FcepsilonRI signaling pathway molecule expression may underlie changes in releasability. CLINICAL IMPLICATIONS: Patients with CIU can be segregated on the basis of basophil functional phenotype.

Basophils↗

PubMed2006

Successful treatment of recalcitrant chronic idiopathic urticaria with sulfasalazine.

BACKGROUND: Antihistamines are the standard treatment for chronic idiopathic urticaria (CIU). For patients whose urticaria is unresponsive to antihistamines, the treatment options are limited. During the previous decade, there have been several case reports demonstrating success with sulfasalazine therapy. In this article, we present a case series evaluating sulfasalazine therapy for antihistamine-unresponsive CIU. OBSERVATIONS: Nineteen patients with antihistamine-unresponsive CIU were treated with sulfasalazine between 2002 and 2005. During sulfasalazine therapy, 14 patients (74%) reported significant improvement, 4 patients (21%) reported minimal improvement but were not satisfied with their symptom relief, and 1 patient (5%) reported a worsening of symptoms. Of the 13 patients who required systemic steroids to control their urticaria, all were able to reduce or discontinue steroid use during sulfasalazine therapy. Although 7 patients (37%) had adverse effects (eg, nausea, headache, mild or transient leukopenia, and transaminitis) that were thought to be caused by the use of sulfasalazine, they all kept taking the drug. CONCLUSIONS: This case series demonstrates that sulfasalazine can be a successful and safe treatment option for patients with CIU who have not responded adequately to treatment with antihistamines. Sulfasalazine was steroid sparing in all subjects who were steroid dependent.

Adolescent↗

PubMed2005

The immunoglobulin E receptor: expression and regulation.

The interaction of immunoglobulin E (IgE) and its receptors is critical for the manifestation of allergic disease. Currently, IgE receptors include the high-affinity Fc epsilonRI and the low-affinity Fc epsilonRII. Fc epsilonRI is a tetrameric or trimeric complex, and each has distinct expression patterns and unique functional consequences. In general, serum levels of IgE regulate Fc epsilonRI expression, and novel therapies that lower the concentration of IgE have provided insights into the contribution of this receptor in allergic disease. Newer therapies targeting Fc epsilonRI-signaling elements and the low-affinity IgE receptor, Fc epsilonRII (CD23), are being developed.

Animals↗

PubMed2005

Basophils and mast cells in chronic idiopathic urticaria.

Chronic idiopathic urticaria (CIU) is diagnosed in patients when urticarial eruptions recur for more than 6 weeks, and no specific cause is determined. Given that urticaria resembles the lesions induced by injection of histamine or allergen into the skin, a role for mast cells or basophils has been proposed in the generation of localized urticarial lesions. However, currently, the exact mechanisms governing regional mast cell or basophil activation are unknown. In the past decade, there has been mounting interest in viewing CIU as an autoimmune disease, given the presence of circulating autoantibodies to IgE or the alpha subunit of the high-affinity IgE receptor (FceRI) in a subset of patients. In this review, we propose that in addition to autoantibodies, specific differences in the expression of FceRI-signaling molecules in the basophils or mast cells of CIU patients may contribute to the generation of urticarial eruptions.

Autoantibodies↗

PubMed2005

Immunological methods for quantifying free and total serum IgE levels in allergy patients receiving omalizumab (Xolair) therapy.

Omalizumab (humanized-IgG1 anti-human IgE Fc, Xolair) complexes circulating IgE, blocking IgE binding to high affinity epsilon Fc receptors (FcepsilonR1) on mast cells and basophils. Free (non-Omalizumab bound) IgE levels in serum are a measure of effective Omalizumab dosing. The goal of this study was to quantify free (non-Omalizumab-complexed) and total serum IgE levels in asthma patients on Xolair. The concentration of (non-Omalizumab bound) free IgE in human serum was measured using a solid phase immunoenzymetric assay (IEMA) in which IgE was captured from serum with monoclonal anti-human IgE (clone HP6061) and detected with labeled-FcepsilonR1alpha. In a companion total human serum IEMA, IgE was captured from serum with the same anti-human IgE (clone HP6061) and all bound IgE was detected with labeled monoclonal anti-human IgE Fc (clone HP6029). Free and total IgE levels were quantified in pre- and 1 and 3 months post Omalizumab therapy sera from 12 allergic asthma patients. In the absence of Omalizumab, working ranges of the free and total IgE IEMAs were comparable (10-1000 kIU/l), with excellent precision, reproducibility and parallelism. Pre-Omalizumab total and free IgE levels by IEMA were highly correlated (r2=0.99, Y=0.9X+0.32, p<0.001), as were total serum IgE levels by IEMA and ImmunoCAP-250 (r2=0.98, Y=1.1X-0.05, p<0.001, n=33). In vitro reduction of free IgE (>90%) occurred at [Omalizumab:IgE] molar ratios of 2-20. Total IgE levels in 12 asthmatics increased from pre-therapy levels (52-658 kIU/l) by 1.5-5.5-fold at 1 month and 1.7-8.6 fold at 3 months of uninterrupted Omalizumab treatment. Free IgE levels fell by 49%-97% at 1 month and 45%-98% by 3 months of Omalizumab treatment. Free and total IgE levels by IEMA aid in monitoring patients receiving Omalizumab therapy.

Adult↗

PubMed2002

How IgE upregulates the allergic response.

For several decades it has been known that IgE is central to the allergic response. In recent years, however, IgE has been described as having several actions in addition to passively arming the mast cell or basophil by binding to their high affinity IgE receptors. Recent studies have revealed roles for IgE in the regulation of its own receptor expression and in contributing to cell survival. Furthermore, the presence of trimeric high-affinity IgE receptors on leukocytes other than mast cells and basophils, together with the discovery of previously unknown functions of the beta subunit of the complex, has added to the complexity of IgE modulation of the allergic response.

Humans↗

PubMedDate not supplied

Atopic dermatitis or hyper-IgE syndrome?

A case of atopic dermatitis (AD), recurrent infections, and elevated immunoglobulin E (IgE) level is presented. Clinical characteristics, pathophysiology, diagnosis, and management in this patient are reviewed. Clinical pearls and pitfalls include the following: (1) deep-seeded Staphylococcus aureus infections occur rarely in AD and should raise the possibility of immunodeficiency syndromes such as hyper-IgE syndrome (HIES); (2) HIES is characterized by a clinical triad consisting of elevated serum IgE levels, recurrent staphylococcal skin abscesses, and pneumonia with pneumatocele formation; (3) although serum IgE levels in AD have been noted to be as high as 10,000 IU/mL, severe cases of AD such as that presented here can exceed this range; (4) the efficacy of anti-IgE therapy in AD or HIES is unknown and may be limited by dosing requirements.

Antibodies, Anti-Idiotypic↗