This work analyzes the hypothesis that human CD38 may cooperate with MHC Class II by acting as coreceptor in a superantigen-induced activation. The initial evidence is that CD38 ligation by specific monoclonal antibodies inhibits superantigen-induced T lymphocyte proliferation. Inhibitory effects become apparent after engagement of CD38 expressed by monocytes, whereas ligation of CD38 expressed...

It has been established that at least some V beta 17+ T cells interact with an endogenous superantigen encoded by the murine retrovirus, Mtv-9. To analyze the role of major histocompatibility complex (MHC) class II molecules in presenting the Mtv-9 encoded superantigen, vSAG-9 to V beta 17+ hybridomas, a panel of nine hybridomas was tested for their ability to respond to A20/2J (H-2d) and LBK (...

Statins are widely used for treatment of hypercholesterolemia. Recent experimental studies revealed that these drugs also exert anti-inflammatory effects. The aim of this study was to assess immunomodulatory effects of statins in humans in vivo. Twenty-seven healthy volunteers were analyzed for serum cytokines and acute phase proteins, HLA-DR and CD38 expression on T cells and superantigen-medi...

Several studies have suggested that there is a direct interaction between the T cell receptor (TCR) and the major histocompatibility complex (MHC) molecule during T cell recognition of superantigen. To further investigate this possibility, we have analyzed T cell recognition of a bacterial superantigen, Staphylococcal enterotoxin B (SEB), presented by a series of mutant murine I-Ek molecules in...

BACKGROUND Rheumatoid arthritis (RA) is the most common chronic inflammatory disease. The staphylococcal superantigens are considered as the causative agent of RA disease. OBJECTIVES This study aimed to assess the presence of staphylococcal enterotoxin D in synovial fluid and blood of patients with RA. PATIENTS AND METHODS A total of 120 blood and SF samples of patients with RA were studied...

The effective functioning of the adaptive immune system requires careful clonal regulation within the B cell compartment. Some microbial pathogens produce virulence factors, like staphylococcal protein A, which interact at high frequencies with B lymphocyte through unconventional binding sites in BCR variable region frameworks conserved during evolution. We have characterized the in vivo effect...

Staphylococcal protein A (SpA), acting as a B cell superantigen, binds to the Fab region of human VH3+ Igs. Using SpA abrogated of its IgG Fc binding activity (Mod SpA) as a model B cell superantigen, we determined whether such an interaction causes complement activation. Addition of Mod SpA to human serum led to complement consumption and the generation of C3a. To determine whether this comple...

Negative selection refers to the selective deletion of autoreactive thymocytes. Its molecular mechanisms have not been well defined. Previous studies in our laboratory have demonstrated that retinoic acids, physiological ligands for the nuclear retinoid receptors, selectively inhibit TCR-mediated death under in vitro conditions, and the inhibition is mediated via the retinoic acid receptor (RAR...

Little is know about the nature of peripheral B cell tolerance or how it may vary in distinct lineages. Although autoantibody transgenic studies indicate that anergy and apoptosis are involved, some studies claim that receptor editing occurs. To model peripheral B cell tolerance in a normal, polyclonal immune system, we generated transgenic mice expressing an Igκ-light chain-reactive superantig...

Enterotoxins with superantigenic properties secreted during systemic Staphylococcus aureus infection are responsible for toxic shock. We show that intranasal administration of staphylococcal enterotoxin A (SEA), but not a recombinant SEA lacking superantigenic activity, protected mice against lethal systemic SEA challenge. Protection was superantigen specific since intranasal exposure to SEA wo...