Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.

Alternative Complement Pathway-Mediated Lysis of Measles Virus Infected Cells: Induction by IgG Antibody Bound to Individual Viral Glycoproteins and Comparative Efficacy of F(ab′)2 and Fab′ Fragments

Abstract: Lysis of measles virus-infected cells by human serum is dependent on IgG antibody and an intact alternative complement pathway The binding sites of IgG measles virus antibody, or its fragments, on the surface of measles virus-infected cells were determined by cell surface radioiodination and immunoprecipitation It was found that IgG bound to either of the two measles virus surface glycoproteins was effective in inducing cell lysis by the alternative pathway Thus, IgG bound only to the viral hemagglutinin (HA) or only to the fusion protein (F) could induced lysis in C4-depleted human serum; the same number of IgG molecules bound to either HA or F induced equivalent dose-related lysis Divalent antibody bound preferentially to HA on the surface of intact cells; this enabled antibody to F to be obtained free of antibody to HA by adsorption Quantitative studies of binding and lysis showed that lysis of measles virus-infected cells by whole or C4-depleted serum required binding of at least 10 times more Fab′ than F(ab′) 2 or IgG molecules per cell In these experiments, C4-depleted serum was quantitatively and kinetically equivalent to whole serum in mediating lysis of measles-infected cells Hence, the binding of IgG to either of the two measles viral polypeptides (HA, F) expressed on the surface of infected cells induces lysis by the alternative pathway, and there is a clear requirement for divalency for effective induction of lysis

Selective immunosuppressive action of a factor produced by colon cancer cells.

Abstract: A soluble substance (HT29 factor) produced by HT29 colon cancer cells markedly suppresses mitogen-induced T-cell proliferation and interleukin-2 production. In this study the range of T-cell functions susceptible to the inhibitory effects of the HT29 factor was evaluated. Serum-free conditioned medium was collected from confluent cultures of HT29 cancer cells, concentrated, and subjected to gel filtration chromatography and anion exchange chromatography, resulting in 24.4-fold purification of the HT29 factor with 31% yield. This factor abolished the development of lymphokine-activated killer cells when present during activation of peripheral blood lymphocytes by interleukin-2 but did not affect the lysis of target cells by normal effectors when added in the lysis stage only. The HT29 factor did not affect the generation of concanavalin A-induced suppressor lymphocytes, even though it markedly inhibited synthesis of DNA, RNA, and protein as well as expression of the CD25 (Tac) antigen during mitogen activation of T-cells. The HT29 factor itself did not induce suppressor cells. These results indicate that the immunosuppressive action of the HT29 factor is selective.

Lysis of microcystis aeruginosa (kütz.) by bdellovibrio‐like bacteria1

Abstract: Cells of Microcystis aeruginosa (Kutzing), collected from water-blooms of Lake Varese, were lysed by Bdellovibrio-like bacteria. The cells were lysed only after penetration. The cyanobacteria and lysing bacteria were characterized by a fibrous glycocalyx. Once the host cell was penetrated, the bacteria remained localized mainly between the host cell wall and cytoplasmic membrane, which appeared partially thickened. Cell lysis began by breakdown of cell structures. The cell wall appeared broken at many sites, and in completely lysed cells, was partially interrupted. The lysis of Microcystis by bacteria could be one of the causes of the death of algal blooms.

Lysis and protoplast formation of group B streptococci by mutanolysin.

Abstract: Group B streptococci, refractory to previously tested muralysins under physiological conditions, were successfully converted to protoplasts by use of a recently describede N-acetyl muramidase, mutanolysin, derived from a streptomycete. Purified enzyme was effective, but crude preparations, although degrading cell walls, simultaneously produced peculiar effects of cytoplasmic coagulation, retention of cell shape, loss of some intracellular enzymes, and a rise in optical density. Addition of purified mutanolysin to the array of muralysins (group C streptococcal phage-associated lysin, lysozyme), previously successful in preparing protoplasts of different streptococci, now makes possible enzymatic preparation of protoplasts of streptococci of groups A, B, C. D. G, and H.