Lysis

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

Cellular Immunoadsorbents: a Simplified Technique for Separation of Lymphoid Cell Populations

Abstract: A simplified and efficient technique for separating T lymphoid cells from non-T cells of mouse, rat and man has been developed. The fractionation procedure is based on the capacity of non-T lymphoid cells to bind antigen-antibody complexes through an Fc receptor. Lymphoid cells are adsorbed on antibody-coated sheep erythrocyte (EA) monolayers prepared in polystyrene Petri dishes previously treated with poly-l-lysine. Adsorption of spleen cells on these monolayers, assisted by a 5-min centrifugation, resulted in 90 to 98% depletion of the Fc receptor-bearing cells (mostly B lymphocytes, but also macrophages and polymorphonuclear leukocytes) in the non-adherent cell population. Eighty to 90% of the adherent cells were capable of forming EA rosettes and could be recovered after lysis of the erythrocytes. The non-adherent fraction comprised at least 90% T-cells. This was determined for mouse and rat spleen cells by lysis with anti-thymocyte serum and complement, and by the absence of immunoglobulin-bearing cells. The specificity of the adsorption was further substantiated by the following observations: 1) lymphoid cells lacking an Fc receptor were not adsorbed; 2) the adsorption to EA monolayers was inhibited by antigen-antibody complexes or by aggregated γ-globulin; and 3) only 10 to 15% of the Fc receptor-bearing cells were attached to non-sensitized erythrocyte (E) monolayers. Fractionation of spleen cells obtained from rats immunized against a syngeneic tumor yielded two separate fractions of cytotoxic lymphoid cells: one (non-adherent, T cells) mediating direct target cell destruction, and the other (adherent, non-T cells) mediating lysis of antibody-coated target cells.

Homologous species restriction in lysis of erythrocytes by terminal complement proteins

Abstract: The cytolytic efficiency of the terminal complement protein complex, C5b-9, varies with the species of origin of C8 and C9. In the present study, we explored the susceptibility of erythrocytes from various species to lysis by C5b6,7 plus C8 and C9 from different species. EC5b6,7 intermediates were prepared on human, guinea pig, rabbit, mouse, and rat erythrocytes with human C5b6 and guinea pig C7. The degree of lysis of these intermediates by C8 and C9 was found to vary widely depending on the species of the proteins and the target cells. In all cases, lysis was least efficient when C8 and C9 were homologous with respect to the target cell species. This effect was mostly attributable to C9. The inefficient lysis in a homologous system is not due to a failure of C9 binding. Rather, the poor lysis in the homologous system may be attributable to inefficient insertion or channel formation.

The lysis of group a hemolytic streptococci by extracellular enzymes of streptomyces albus : i. production and fractionation of the lytic enzymes

Abstract: The lysis of group A hemolytic streptococci by extracellular enzymes of Streptomyces albus has been studied. The most favorable material for fractionation of the lytic enzymes was obtained by surface growth on shallow layers of liquid medium containing an acid hydrolysate of casein, glucose, and salts. The results of fractionation experiments show that the potent proetolytic enzyme of Streptomyces albus is not able to lyse group A streptococci, and that the initiation of lysis is dependent upon the action of a second, non-proteolytic enzyme. The nature of the non-proteolytic enzyme has not been determined. It does not appear to be a ribonuclease or a lysozyme-like enzyme.

Morphogenic effects of alpha-factor on Saccharomyces cerevisiae a cells.

Abstract: Saccharomyces cerevisiae mating type a cells enlarged and elongated when exposed to alpha-factor, a sex pheromone produced by mating-type alpha cells. This morphogensis required exogenous-D-glucose, nitrogen, and phosphate, and cells in exponential phase responded better than stationary-phase cells. Morphogenesis was blocked by cycloheximide and by inhibitors of cell wall biosynthesis such as 2-deoxy-D-glucose, 2-deoxy-2-fluoro-D-glucose, and 2-deoxy-2-fluoro-D-mannose, but not by polyoxin D. One to two hours after addition of pheromone, a cells became more susceptible to lysis by glucanases, a change that was dependendent on the dose of alpha-factor and was blocked by drugs that block morphogenesis. On the other hand, treatment with alpha-factor did not increase susceptibility to attack by trypsin, subtilisin, or exo-alpha-mannanase. Radioactive label, incorporated into cell wall polysaccharides during treatment with alpha-factor, was not secreted into the medium during morphogenesis. Analysis of the labeled wall polymers showed that alpha-factor-treated cells contain more glucan and less mannan than control cells, and that the mannan of treated cells contains an increased proportion of shorter side chains and unsubstituted backbone mannose units. Thin-section electron microscopy of treated cells revealed that the cell wall possesses a diffuse outer layer in the extension and is thinner at the tip.