Recognition of conventional foreign antigen by T cells is determined by the expression of multiple variable regions of both ol and 3 chains of the T cell receptor (TCR) oe/3 heterodimer. In contrast, there exists a class of antigens that appears to interact with the TCR c~/3 heterodimer through the variable region on the 3 chain (V3), independent of other TCR components, a property that has led...

The immune response to mouse mammary tumor virus (MMTV) relies on the presentation of an MMTV-encoded superantigen by infected B cells to superantigen-specific T cells. The initial extrafollicular B cell differentiation involved the generation of B cells expressing low levels of B220. These B220low B cells corresponded to plasmablasts that expressed high levels of CD43 and syndecan-1 and were C...

Stimulation of mature CD4 cells through the TCR induces cellular activation and expansion that are often followed by clonal elimination by a form of apoptosis termed activation-induced cell death. This process of CD4 cell apoptosis is generally thought to reflect clonal suicide and to be independent of other cell types. Here we show that during the response to the superantigen Staphylococcal en...

Superantigens are microbial agents that have a strong effect on the immune response of the host. Their initial target is the T lymphocyte, but a whole cascade of immunological reactions ensues. It is thought that the microbe engages the immune system of the host to its own advantage, to facilitate persistent infection and/or transmission. In this review, we discuss in detail the structure and f...

The mouse mammary tumor virus-7 superantigen (vSAG7) is proteolytically processed in B cells at as many as three positions. Proteolytic processing appears to be important for superantigen activity because a processed form of vSAG7 was predominant among those forms that were found to bind to major histocompatibility complex class II molecules. To determine the functional significance of proteoly...

PCR was employed to determine the presence of all known superantigen genes (sea, seq, and tst) and of the exotoxin-like gene cluster (set) in 40 Staphylococcus aureus isolates from blood cultures and throat swabs; 28 isolates harbored superantigen genes, five on average, and this strictly correlated with their ability to stimulate T-cell proliferation. In contrast, the set gene cluster was dete...

Presentation of the Mtv-1 superantigen (vSag1) to specific Vbeta-bearing T cells requires association with major histocompatibility complex class II molecules. The intracellular route by which vSag1 trafficks to the cell surface and the site of vSag1-class II complex assembly in antigen-presenting B lymphocytes have not been determined. Here, we show that vSag1 trafficks independently of class ...

Transgenic mice expressing either the mouse mammary tumor virus (MMTV) superantigen gene (sag) alone or in combination with the viral envelope genes (env) (LEL), or all of the viral genes (gag, pol, env, and sag) (HYB PRO), deleted V beta 14+ T cells from their immune repertoire. However, only LEL or HYB PRO transgenic antigen-presenting cells were capable of stimulating a proliferative respons...

Superantigens interact with the immune system by binding to major histocompatibility complex (MHC) class II proteins and activating T cells through the variable region of the T cell receptor beta-chain. Through this means they can cause massive proliferation and then death of a large proportion of T cells. Superantigens are produced by bacteria, mycoplasmas, retroviruses, and probably by other ...

Staphylococcal enterotoxin B (SEB) is both a superantigen and toxin. As a superantigen, SEB can bind to major histocompatibility complex (MHC) class II molecules to form a ligand for ot/B T cell receptors bearing particular VB elements. As a toxin, SEB causes rapid weight loss in mice sometimes leading to death. We show here that both of these functions map to the NH2-terminal portion of the to...