Molecular features of the cytolytic pore-forming bacterial protein toxins.

The repertoire of the cytolytic pore-forming protein toxins (PFT) comprises 81 identified members. The essential feature of these cytolysins is their capacity to provoke the formation of hydrophilic pores in the cytoplasmic membranes of target eukaryotic cells. This process results from the binding of the proteins on the cell surface, followed by their oligomerization which leads to the insertion of the oligomers into the membrane and formation of protein-lined channels.

Staphylococcal and streptococcal superantigens: molecular, biological and clinical aspects.

Superantigens (SAgs) include a class of certain bacterial and viral proteins exhibiting highly potent lymphocyte-transforming (mitogenic) activity towards human and or other mammalian T lymphocytes. Unlike conventional antigens, SAgs bind to certain regions of major histocompatibility complex (MHC) class II molecules of antigen-presenting cells (APCs) outside the classical antigen-binding groove and concomitantly bind in their native form to T cells at specific motifs of the variable region of the beta chain (Vbeta) of the T cell receptor (TcR). This interaction triggers the activation (proliferation) of the targeted T lymphocytes and leads to the in vivo or in vitro release of high amounts of various cytokines and other effectors by immune cells.

Cytocompatibility study of organic matrix extracted from Caribbean coral porites astroides.

Since 1980, natural coral exoskeleton has been widely used as bone graft substitute. Despite numerous in vitro and in vivo studies. there is still a lack of knowledge concerning the organic matrix associated with coral exoskeleton (COM).

Superantigen bacterial toxins: state of the art.

Superantigens (SAgs) are viral and bacterial proteins exhibiting a highly potent polyclonal lymphocyte-proliferating activity for CD4(+), CD8(+) and sometimes gammadelta(+) T cells of human and (or) various animal species. Unlike conventional antigens, SAgs bind as unprocessed proteins to invariant regions of major histocompatibility complex (MHC) class II molecules on the surface of antigen-presenting cells (APCs) and to particular motifs of the variable region of the beta chain (Vbeta) of T-cell receptor (TcR) outside the antigen-binding groove. As a consequence, SAgs stimulate at nano-to picogram concentrations up to 10 to 30% of host T-cell repertoire while only one in 10(5)-10(6) T cells (0.