434 research outputs found

    Integration of a virus membrane protein into the lipid bilayer of target cells as a prerequisite for immune cytolysis

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    Structural requirements for membrane antigens on target cells to mediate immune cytolysis were studied in a model system with purified membrane proteins from Semliki Forest virus (SFV). These SFV spike proteins were isolated in the form of detergent- and lipid-free protein micelles (29S complexes) or, after reconstitution into lipid vesicles, in the form of virosomes. Both the 29S complexes and the virosomes were found to bind well to murine tumor cells (P815 or Eb). When these cells, however, were used as target cells in complement-dependent lysis or in antibody-dependent cell- mediated cytotoxicity assays in the presence of anti-SFV serum, they were not lysed, although they effectively bound the antibody and consumed complement. The same tumor cells infected with SFV served as positive controls in both assays. Different results were obtained when inactivated Sendai virus was added as a fusion reagent to the cells coated with either virosomes or 29S complexes. Under these conditions the virosome-coated cells became susceptible to SFV- specific lysis, whereas the 29S complex-coated cells remained resistant. Evidence that the susceptibility to lysis ofvirosome-coated cells was dependent on active fusion and, therefore, integration of the viral antigens into the lipid bilayer of the target cells was derived from control experiments with enzyme-treated Sendai virus preparations. The 29S complexes and the virosomes partially and selectively blocked the target cell lysis by anti-H-2 sera but not by anti-non-H-2 sera confirming our previous finding that major histocompatibility antigens serve as receptors for SFV. The general significance of these findings for mechanisms of immune cytolysis is dicussed

    Integration of a virus membrane protein intothe lipid bilayer of target cells as a prerequisite for immune cytolysis. Specific cytolysis after virosome- target cell fusion

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    Structural requirements for membrane antigens on target cells to mediate immune cytolysis were studied in a model system with purified membrane proteins from Semliki Forest virus (SFV). These SFV spike proteins were isolated in the form of detergent- and lipid-free protein micelles (29S complexes) or, after reconstitution into lipid vesicles, in the form of virosomes. Both the 29S complexes and the virosomes were found to bind well to murine tumor cells (P815 or Eb). When these cells, however, were used as target cells in complement-dependent lysis or in antibody-dependent cell- mediated cytotoxicity assays in the presence of anti-SFV serum, they were not lysed, although they effectively bound the antibody and consumed complement. The same tumor cells infected with SFV served as positive controls in both assays. Different results were obtained when inactivated Sendai virus was added as a fusion reagent to the cells coated with either virosomes or 29S complexes. Under these conditions the virosome-coated cells became susceptible to SFV- specific lysis, whereas the 29S complex-coated cells remained resistant. Evidence that the susceptibility to lysis ofvirosome-coated cells was dependent on active fusion and, therefore, integration of the viral antigens into the lipid bilayer of the target cells was derived from control experiments with enzyme-treated Sendai virus preparations. The 29S complexes and the virosomes partially and selectively blocked the target cell lysis by anti-H-2 sera but not by anti-non-H-2 sera confirming our previous finding that major histocompatibility antigens serve as receptors for SFV. The general significance of these findings for mechanisms of immune cytolysis is dicussed

    Minimal deformations of the commutative algebra and the linear group GL(n)

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    We consider the relations of generalized commutativity in the algebra of formal series Mq(xi) M_q (x^i ) , which conserve a tensor Iq I_q -grading and depend on parameters q(i,k) q(i,k) . We choose the Iq I_q -preserving version of differential calculus on Mq M_q . A new construction of the symmetrized tensor product for Mq M_q -type algebras and the corresponding definition of minimally deformed linear group QGL(n) QGL(n) and Lie algebra qgl(n) qgl(n) are proposed. We study the connection of QGL(n) QGL(n) and qgl(n) qgl(n) with the special matrix algebra \mbox{Mat} (n,Q) containing matrices with noncommutative elements. A definition of the deformed determinant in the algebra \mbox{Mat} (n,Q) is given. The exponential parametrization in the algebra \mbox{Mat} (n,Q) is considered on the basis of Campbell-Hausdorf formula.Comment: 14 page

    Representations of the quantum matrix algebra Mq,p(2)M_{q,p}(2)

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    It is shown that the finite dimensional irreducible representaions of the quantum matrix algebra Mq,p(2) M_{ q,p}(2) ( the coordinate ring of GLq,p(2) GL_{q,p}(2) ) exist only when both q and p are roots of unity. In this case th e space of states has either the topology of a torus or a cylinder which may be thought of as generalizations of cyclic representations.Comment: 20 page
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