The myeloid cell–specific expression and interferon(IFN) induction of Fc receptor I (Fc RI) requires cooperation between PU.1 and signal transducer and activator of transcription 1 (Stat1) by means of mechanisms that are unknown. We found that PU.1 and Stat1 mediated distinct functions in the activation of Fc RI promoter. The basal activity of the natural Fc RI promoter was strictly dependent o...

Soluble IgE receptors are potential in vivo modulators of IgE-mediated immune responses and are thus important for our basic understanding of allergic responses. We here characterize a novel soluble version of the IgE-binding alpha-chain of Fc-epsilon-RI (sFcεRI), the high affinity receptor for IgE. sFcεRI immunoprecipitates as a protein of ∼40 kDa and contains an intact IgE-binding site. In hu...

Protein kinase C (PKC) plays a prominent role in immune signaling, and the paradigms for isoform selective signaling are beginning to be elucidated. Real-time microscopy was combined with molecular and biochemical approaches to demonstrate a role for PKC- epsilon in Fc gamma receptor (Fc gammaR)-dependent phagocytosis. RAW 264.7 macrophages were transfected with GFP-conjugated PKC isoforms, and...

Upon contact with allergen, sensitized mast cells release highly active proinflammatory mediators. Allergen-mediated mast cell activation is an important mechanism in the pathogenesis of atopic asthma. Asthmatic patients are especially susceptible to air pollution. Epidemiologic studies found a positive correlation between severity of symptoms among asthmatic patients and the level of particula...

Activation of Ras GTPases is a conserved feature of antigen receptor signaling, including Fc epsilon R1 activation of mast cells. Antigenic cross-linking of the Fc epsilon R1 on mast cells results in secretion of allergic mediators and induction of immediate early and cytokine genes. Here we examine the role of Ras in coupling the Fc epsilon R1 to transcriptional regulation. The transcription f...

particular individual to an allergen is more intense than that of another are poorly understood. However, the and Jean-Pierre Kinet importance of genetic background in the development Laboratory of Allergy and Immunology of atopic disease is underscored by the tendency of Department of Pathology severe atopic disease to run in families. Recently, sev-Beth Israel Hospital eral studies have repor...

Two hybridomas that produce the mAbs 135 and 449 B4 were obtained that inhibited the binding of IgE to the Fc epsilon RL/CD23 on the EBV-transformed B cell line RPMI 8866. mAb 135 was obtained from a mouse immunized with RPMI 8866 cells, whereas mAb 449B4 was obtained from a mouse immunized with a partially purified preparation of Fc epsilon RL/CD23 obtained as the eluate of an IgE immunoabsorb...

One of the major functions of the N-formyl peptide receptor (FPR) is to mediate leukocyte degranulation. Phosphorylation of the C-terminal domain of the FPR is required for receptor internalization and desensitization. Although arrestins mediate phosphorylation-dependent desensitization, internalization, and initiation of novel signaling cascades for a number of G protein-coupled receptors, the...