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At least 19 recordsLinked to original sources
PubMed1975

Lysis of tumor cells by antibody and complement. II. Lack of correlation between amount of C4 and C3 fixed and cell lysis.

Two antigenically distinct diethylnitrosamine-induced guinea pig hepatoma cell lines, line-1 and line-10, sensitized with rabbit anti-Forssman or with tumor-specific antibody, were more susceptible to killing by human complement (HuC) than by guinea pig complement (GPC). This difference could not be ascribed to differences in the amount of C1, C4, and C3 fixed: millions of C4 and hundreds of thousands of C3 were detected on cells whether they were killed or not killed by the C sources. Tumor cells sensitized with anti-Forssman IgM antibody generally had more GP C4 and C3 than Hu C4 and C3 bound to their surfaces. Cells sensitized with anti-tumor antibody generally had more Hu C4 and C3 than GP C4 and C3 bound to their surfaces. The resistance to killing of nucleated cells by antibody and C may be due in part to intrinisic properties of the cell.

Animals↗
PubMed1975

In vitro target cell lysis mediated by normal human lymphocytes (K cells) or monocytes.

Guinea pig IgG1 or IgG2 anti-dinitrophenyl (DNP) Antibody preparations were used for induction of target cell lysis by normal human lymphocytes (K cells) or monocytes. Target cells were DNP-coated 51Cr-labeled chicken erythrocytes. Antibody concentrations were assayed by an ammonium sulphate precipitation technique. When antiserum was obtained by immunization with the antigen in Freund's complete adjuvant (FCA), IgG2 antibodies predominated and were significantly more efficient inducers of K-cell-mediated lysis than IgG1 antibodies. The lowest activity in K-cell-mediated lysis was seen with IgG1 from antiserum obtained by immunization with antigen in Freund's incomplete adjuvant. When these antibody fractions were tested in monocyte-mediated erythrolysis, the two IgG1 fractions were as active as the IgG2 antibodies raised with antigen incorporated in FCA. The results suggest that the Fc receptors of mature human blood monocytes are different from those on the effector cells in the K-cell preparations.

Animals↗
PubMed1976

[BPO-Specific, complement-dependant cell-lysis of differently sensitized sheep red cells: evaluation of haptenic groups and their influence on IgM and IgG-induced lysis (author's transl)].

Sheep erythrocytes were coated with bencylpenicilloyl-(BPO)groups. Different incubation periods resulted in erythrocyte preparations with different hapten density. Complement dependent lysis induced by IgM or IgG antibodies was studied with the cell preparations. The calculation of hapten density on the erythrocyte surface was not possible by direct measurement of coupled radioactive BPO since more than 90% of radioactive material was found in the soluble supernatant after osmotic cell lysis and less than 10% was fixed to the cellular membrane. Measurement of membrane bound immunologically relevant BPO-groups was achieved, therefore, by comparison of the inhibitory capacity of the test cells with that of a standard cell preparation. The latter consisted of tannic acid treated erythrocytes coated with protein complexed radioactive BPO. Surface hapten density of the different target cell preparations varied between 1.9 x 10(5) and 4.8 10(5) BPO-groups per cell depending on the time of incubation. Complement dependent antibody mediated cell lysis was significantly reduced by reduction of haptenic sites per target cell, IgG induced lysis being much more affected than hemolysis induced by IgM antibodies. Statistical calculations led to the conclusion that 18,000 protein islets per cell bearing 4 or more BPO-groups are not sufficient for hemolysis induced by IgG antibodies. 48,000 protein islets with this hapten density are necessary for "optimal" sensitization. IgG antibodies must be apparently bound to the cell surface in bivalent form.

Cell Membrane↗
PubMed1977

Genetic and physiological control of host cell lysis by bacteriophage lambda.

The timing of host cell lysis at the end of the lytic cycle of phage lambda is under complex control. The lambda S protein stimulates lysis. Another physiological system, the lysis regulator, inhibitis lysis from occurring prematurely. The effects of a series of phage and bacterial mutations on these controls are described. They show that the lambda rex gene plays a role in regulating lysis under suboptimal growth conditions. In certain mutant cells, and especially under anaerobic culture conditions, the rex gene aids in the scheduling of host cell lysis. The data also suggest that the lysis regulator may control the transition of the lambda S protein from an inactive to an active state.

Anaerobiosis↗
PubMed1979

Microcinematographic and electron microscopic analysis of target cell lysis induced by cytotoxic T lymphocytes.

A study was carried out to determine the sequence of events of T-cell mediated target cell lysis in microcinematography and electron microscopy. Highly efficient cytotoxic T lymphocytes (CTL) were generated in vivo and in vitro using preimmunized spleen cells and purification procedures. Such CTL were highly specific. This specificity correlated well with the number of adhesions formed between CTL and targets and this criterion was used to study killer-target cell interaction. Microcinematography showed that target cell lysis at the single cell level, despite time variations, could be clearly separated into three phases: (a) a recognition phase, visible by random crawling of CTL over the target cell surface until firm contact was established; (b) a post-recognition phase, during which firm contact between CTL and target was maintained without gross modification of either cell; (c) a phase of target cell disintegration, mainly characterized by vigorous blebbing of the cell membrane resulting in a motionless carcass of the target cell but not in its total dissolution. Only later this carcass decayed and formed a necrotic ghost. Electron microscopic observations were put into sequence according to microcinematography. Post-recognition phase was characterized by a tight apposition of the membranes of CTL and target cell. No gap junctions could be observed. During target cell disintegration, profound cytoplasmic and nuclear changes occurred simultaneous with surface blebbing. Most noticeable were extensive internal vacuolization, mitochondrial swelling, nuclear pycnosis and dissolution of the nucleolus. These observations suggested that target cell lysis does not start with a surface phenomenon similar to complement lysis, but a process involving practically the whole cell simultaneously. It is conceivable, therefore, that the signal from the CTL is transmitted across the target cell, and that the switch to sudden cell death is manipulated deep inside the cell.

Animals↗
PubMed1979

Amniotic fluid cell culture II. Evaluation of a red blood cell lysis procedure for culture of cells from blood-contaminated amniotic fluid.

Second trimester amniotic fluid samples obtained transabdominally for genetic analysis not infrequently are contaminated with blood. There has been disagreement as to whether blood contamination interferes with the efficiency of culture of amniotic fluid cells for genetic diagnosis. A procedure using ammonium chloride to lyse contaminating red blood cells has been recommended to increase culture success. In this report we document that cultures derived from blood-contaminated amniotic fluids form fewer cell colonies than cultures from clear amniotic fluids. We also show that a recommended procedure using ammonium chloride to lyse red blood cells is ineffectual in improving the efficiency of cell culture, and may be detrimental to successful culturing of cells from bloody amniotic fluids. A hypothesis concerning the mechanism of interference with culture of amniotic fluid cells by contaminating blood is presented and a means of preventing this complication is suggested.

Ammonium Chloride↗
PubMed1976

Early steps in specific tumor cell lysis by sensitized mouse T lymphocytes. II. Electrolyte permeability increase in the target cell membrane concomitant with programming for lysis.

In a previous study of the mechanism of specific target cell lysis by alloimmune cytolytic T lymphocytes (CTL), we established that the target cell becomes irreversibly programmed to lyse within a few minutes after contact with the CTL. We here show that at each point in time, the level of specific release of the potassium analog, 86Rb equals the percentage of target cells which have been programmed to lyse. It is also shown that specific release of 86Rb is more rapid than that of a small metabolite of similar weight, 14C-nicotinamide, which in turn is specifically released more rapidly than 51Cr. Thus, an electrolyte-permeable lesion is produced in the target cell membrane within minutes of contact with the CTL. Since measurements of 86Rb release, unlike measurements of programming for lysis, do not involve exposure of the cells to EDTA and vigorous shearing forces, the present observations corroborate and extend, by an independent and gentler method, our previous conclusion that the CTL effects crucial and irreversible changes in the target cell within minutes after contact. The present results are consistent with the possibility that the first, and perhaps the only damage administered directly by the CTL is a membrane lesion permeable to electrolytes and possibly to small molecules.

Animals↗
PubMed1978

Studies on the mechanism of action of guinea pig lymphotoxin. I. Membrane active substances prevent target cell lysis by lymphotoxin.

The effect of various pharamacologic agents on lysis of L cells by guinea pig lymphotoxin (LT) was studied. Among the many drugs tested, only those that affect plasma membrane functions were found to interfere with the cytolytic action of LT. Dimethyl sulfoxide or lidocaine potentiated L cell resistance against lysis. Stronger protection was provided by ouabain. Addition of ouabain to cells previously injured by LT was also effective in reducing cell death. Attempts to detect metabolic disturbances in cells before LT cytolysis were unsuccessful. The biosynthetic rate of DNA, RNA, or protein, and the total cellular content of ATP were not significantly changed in LT-treated cells. The results suggest that LT disturbs some plasma membrane functions of the target cell, perhaps ion transport systems, and consequently induces ionic imbalances between the intra-and extracellular milieu which eventually cause cell death.

Adenosine Triphosphate↗
PubMed1979

Process characteristics of cell lysis mutants of Saccharomyces cerevisiae.

Several temperature-sensitive lysis mutants of Saccharomyces cerevisiae were selected according to their ability to release alkaline phosphatase when incubated at a nonpermissive temperature. For two mutants, cell lysis and release of alkaline phosphatase reached a maximum when cells in the logarithmic growth phase were shifted to the nonpermissive temperature. Morphological changes, as well as changes in macromolecular composition of the cells, were observed. Growth is necessary and oxygen is important for the expression of cell lysis at the nonpermissive temperature.

Alkaline Phosphatase↗
PubMed1975

Early steps in specific tumor cell lysis by sensitized mouse T lymphocytes. I. Resolution and characterization.

Addition of high molecular weight dextran to culture medium prevents the initiation of T lymphocyte-mediated killing by holding the cytolytic T lymphocytes (CTL) and target cells in suspension and preventing intercellular contact. Suspension in 10% dextran was used to interrupt the ongoing formation of adhesions between CTL and target cells already in contact in a centrifuged pellet. The results demonstrate that 1) firm adhesions form between CTL and target cells within 1 min at 37 degrees C; 2) once formed, these adhesions are stable at low temperature and are resistant to mechanical shearing forces; 3) these adhesions can be disrupted by EDTA; 4) immediately after the adhesions form, separation of the CTL from the target cells prevents lysis of the latter; 5) after incubation of targets adhering to CTL for an additional 6 min at 37 degrees C, removal of the CTL no longer prevents target cell lysis. Thus, target cells become "programmed" for subsequent lysis within a few minutes after contact with CTL, after which lysis occurs during the next several hours without further participation of the effector cell. At 15 degrees C, adhesions form 1/17 as fast as at 37 degrees C. Programming of target cells for lysis occurs 1/76 as fast at 15 degrees C as at 37 degrees C. Thus, the programming for lysis step is about 4-fold more temperature dependent than the adhesion step. In addition to being detected by subsequent target cell lysis in 10% dextran, the adhering cell clusters can be counted with low power microscopy. This permitted verification that EDTA separates the clusters after programming for lysis is complete. Moreover, the great majority of the clusters seen at 37 degrees C are antigen-specific. Knowledge of the cluster size distribution and the subsequent level of lysis permits the deduction that not less than 6% of the sensitized peritoneal cell populations used were CTL.

Animals↗
PubMed1979

ADCC (K-cell) lysis of human erythrocytes sensitized with rhesus alloantibodies. II. Investigation into the mechanism of lysis.

The mechanism of lysis of anti-D coated human erythrocytes by human mononuclear K-cells was investigated. Red cell lysis was measurable after 30 min incubation and reached a maximum by 18--20 h. Cell-to-cell contact was necessary for lysis, phagocytosis was not a prerequisite, and intact microfilament function was required. The divalent cations Ca2+ and Mg2+ were both required for lysis to occur. Studies with metabolic inhibitors indicate that some RNA and protein synthesis is required for maximum expression of ADCC and intact microtubule function is essential. In the present system lysis was mediated by IgG1 anti-D antibodies and was significantly inhibited by IgG1 and IgG3 subclasses with some inhibition by IgG2 but not by IgG4, IgA or IgM. This suggests that the K-cell receptor is specific for IgG but that there is major cross-reactivity between IgG1 and IgG3. The inhibiting effect of hydrocortisone suggests that ADCC inhibition may be one mode of action of corticosteroids in ameliorating autoimmune haemolytic anaemia.

Animals↗
PubMed1978

Antibody dependent cellular cytotoxicity (ADCC) against human erythrocytes, mediated by blood group alloantibodies: a model for the role of antigen density in target cell lysis.

Antibody dependent cellular cytotoxicity (ADCC) of human mononuclear cells against human erythrocytes could be obtained with anti-A and anti-D sera. The degree of lysis varied considerably depending on the antigen system and on the experimental conditions. Anti-D mediated in contrast to anti-A mediated ADCC turned out to be very sensitive to conditions which interfere with target cell lysis: for most of the anti-D sera, removal of unbound IgG was found to be crucial to detect their ability to mediate ADCC. Pretreatment of the target cells with various enzymes dramatically improved specific lysis and left spontaneous release and spontaneous cytotoxicity essentially unaffected. In the case of neuraminidase treatment it could be shown that the effect was independent from the exposure of additional binding sites. When enzyme treatment and removal of excess IgG were applied in combination, as little as 10(4) antigenic determinants proved to be sufficient to induce specific lysis.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1979

Suppression of cell-mediated tumor cell lysis and complement-induced cytotoxicity by trypan blue.

Different forms of cell-mediated cytotoxicity were suppressed in the presence of trypan blue. The systems affected included lysis of antibody-coated tumor cells by normal and C. parvum-stimulated mouse peritoneal cells and lysis of allogeneic targets by immune effector cells. The inhibition, measured in a 4-hr 51Cr release assay, was reversible and did not occur in the presence of 30% fetal calf serum or albumin. Binding between effector and target cells through Fc receptors was not affected, and lysis of allogeneic cells was inhibited at the lytic step rather than at the binding step. In contrast, lysis of sensitized erythrocytes was not inhibited by trypan blue, suggesting that lysis of these targets may not involve the steps required in tumor cell lysis. Trypan blue blocked the function of antibody before binding to target cells and also suppressed complement-induced cytolysis. Most individual complement components were susceptible to the inhibitory action of trypan blue. These results reveal an affinity of trypan blue for proteins in general that may be responsible for many of its biologic actions.

Animals↗
PubMed1978

Quantitative influence of antibody and complement coating of red cells on monocyte-mediated cell lysis.

Monocyte-mediated lysis in vitro of human red cells coated with measured amounts of immunoglobulin G (IgG) or complement were studied. 1,000-1,500 molecules of IgG anti-D are necessary to effect measurable lysis, and lysis increases linearly with increasing levels of antibody sensitization. 100 microgram/ml of IgG1 abolished lysis even at maximal levels of anti-D sensitization (15,000 molecules/cell). Two isoimmune IgG anti-A or anti-B antisera were 5 to 10-fold less efficient in promoting phagocytosis or lysis per molecule of IgG bound; however, because of the greater antigen density of A or B, more than 100,000 molecules IgG/cell could be bound, producing equivalent lysis to anti-D-coated cells. Although inhibition by IgG1 was similar at equivalent levels of sensitization with anti-A, anti-B, or anti-D at high levels of coating with anti-A or anti-B (not attainable with anti-D), lysis was not inhibited by IgG1. Cells coated with human complement components alone were not lysed by monocytes; however, complement coating augmented IgG-mediated lysis and reduced the quantity of anti-D necessary to produce lysis to less than 1,000 molecules/cell. After thorough degradation of C3b by serum to C3d, complement augmentation persisted.

ABO Blood-Group System↗
PubMed1977

Mechanism of target cell lysis of cytolytic T lymphocytes. I. Characterization of specific lymphocyte-target cell conjugates separated by velocity sedimentation.

Differential velocity sedimentation was applied for separating alloimmune T lymphocytes bound to target cells (TC) from free lymphocytes. Maximal size differences between lymphocytes and TC were achieved a) by isolating the fraction of small peritoneal lymphocytes (SPL) from an alloimmune peritoneal cell population, and b) by selecting large tumor cells as TC. Under the conditions used, most of the conjugates formed at room temperature consisted of one SPL bound to one TC, and adequate separation of bound from free SPL could be achieved within less than 5 min. Functional studies of the conjugate-enriched fractions showed that a minimum of 60% of TC-bound SPL were indeed cytolytic. Conjugate-depleted fractions, however, were still lytic, suggesting that not all effector cells formed stable conjugates at room temperature. Transmission and scanning electron microscopy studies revealed that binding between SPL and TC was achieved through interpenetrating membrane projections and was characterized by point and broad zone contacts. When lysis was allowed to proceed, prominent changes of the TC membrane morphology, including loss of microvillous projections, appearance of localized blebs, pseudopod-like projections, and membrane defects were documented.

Animals↗