Showing papers by "Jacov Levy published in 1999"

Defective Self-Reactive Antibody Repertoire of Serum IgM in Patients with Hyper-IgM Syndrome

Abstract: We have analyzed the self-reactive repertoires of IgM and IgG Abs in the serum of 19 patients with hyper-IgM syndrome (HIM) by means of a quantitative immunoblotting technique that allows for a quantitative comparison of Ab repertoires in health and disease by multiparametric statistical analysis. Normal tissue extracts of liver, lung, stomach, and kidney were used as sources of self Ags. Extracts of Pseudomonas aeruginosa and Staphylococcus epidermidis were used as sources of nonself Ags. We demonstrate a significant bias in repertoires of reactivities of IgM of patients with HIM with self Ags. Ab repertoires of IgM toward nonself Ags did not differ, however, between patients and controls. No difference was found between IgM repertoires of untreated patients and those of patients receiving substitutive treatment with i.v. IgG. IgG in the serum of HIM patients lacked reactivity with self Ags, although it exhibited a pattern of reactivity with nonself Ags that was similar to that of IgG of healthy controls. The data demonstrate that functional CD40-CD40 ligand interactions are essential for the selection of natural self-reactive B cell repertoires.

Zinc Supplementation Increases the Level of Serum Insulin-Like Growth Factor-I but Does Not Promote Growth in Infants with Nonorganic Failure to Thrive

Abstract: We investigated in a randomized double-blind placebo-controlled study the effects of zinc supplementation (2 mg/kg/day) for 12 weeks on growth, serum insulin-like growth factor-I (IGF-I) and insulin-l

Identification of a Subset of Common Variable Immunodeficiency Patients with Impaired B-Cell Protein Tyrosine Phosphorylation

Abstract: The mechanisms responsible for common variable immunodeficiency syndrome (CVID) are as yet unknown. In the present study, we show that the B-cell dysfunction in a subset of CVID patients is caused by defective protein tyrosine phosphorylation (PTP). We demonstrated that the PTP level and immunoglobulin (Ig) secretion malfunctions can be successfully repaired when normal plasma membrane components are implanted into these patients’ B cells. Stimulation of CVID patients’ peripheral blood mononucleated cells with anti-Ig antibody revealed that 7 of 11 patients had lower PTP levels than those found in the normal donor cells. Plasma membrane implantation to the cells of these patients resulted in elevated PTP levels which reached normal levels upon stimulation with anti-human Ig antibody. The results revealed two distinct groups of CVID patients. The first group included patients whose B cells expressed low PTP levels after Ig stimulation. In these patients the plasma membrane implantation restored the normal PTP level as well as the ability to secrete IgM and/or IgG after B-cell stimulation. In the second group, patients whose B cells expressed a normal PTP level after Ig stimulation, with no restoration of their ability to secrete Ig upon plasma membrane implantation and lipopolysaccharide stimulation. We conclude that the first group has an early signal transduction defect located in the B-cell plasma membrane, while in the second group the defect is located elsewhere.