Recognition of typhus group rickettsia-infected targets by human lymphokine-activated killer cells

Biotechnology and biomimetic with crystalline bacterial cell surface layers (S-layers)

Crystalline bacterial cell surface layers (S-layers) are the outermost cell envelope component of many eubacteria and archaeobacteria. S-layers are composed of a single protein or glycoprotein species and exhibit oblique, square or hexagonal lattice symmetry. Pores passing through these monomolecular arrays show identical size and morphology, and functional groups are aligned in well-defined positions and orientations. Due to these unique features, S-layers have broad application potential in biotechnology including functioning as biomimetic membranes. Presently, S-layers are used (i) for the production of isoporous ultrafiltration membranes with very well defined molecular sieving and adsorption properties, (ii) as matrices for the controlled immobilization of biologically active macromolecules (e.g., enzymes, antibodies, ligands) as required for biosensors, affinity membranes and affinity microparticles as well as for solid phase assays, (iii) as stabilizing structures for Langmuir-Blodgett films and liposomes and (iv) as carriers and adjuvants for weakly immunogenic antigens and haptens.

The importance of the crystalline surface layer protein antigens of rickettsiae in T-cell immunity

Studies in animal models have demonstrated that solid immunity to typhus rickettsiae is dependent on immune T cells. In addition, the surface protein antigen (SPA) of typhus rickettsiae has been shown to be an effective immunogen, protecting vaccinated animals against subsequent challenge with virulent organisms. In the present studies we describe three classes of human lymphocytes which are capable of lysing cells infected with typhus rickettsiae. The first class is CD3,8-positive and is capable of specially lysing both HLA-matched and mismatched targets infected with typhus rickettsiae. Since this cytotoxic effector can be generated with IL-2 as well as with SPA it appears to be a lymphokine-activated killer (LAK). The second class of lymphocytes is CD3,4-positive and is capable of producing gamma interferon in response to the SPA of typhus rickettsiae. Gamma interferon in turn can cause the lysis of cells infected with typhus rickettsiae as well as inhibit intracellular rickettsial growth. A third cytotoxic effector which is CD3,4-positive and which is capable of lysing only HLA-matched targets infected with typhus rickettsiae was generated with a sonicated antigen, and its fine antigenic specificity is not known at present. We conclude that the SPA is an immunologically important protein for the human host and represents an outstanding candidate for a subunit vaccine against typhus.