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Lymph node and spleen cells from normal mice were cultured for 3 days with polyoma virus-induced tumour, Ehrlich's ascites turnout or leukaemia L 1210 cells. This resulted in in vitro immunization of the lymphocytes, which were then transferred to irradiated target cells labelled with 51Cr. Normal, i.e. non-immune thioglycollate-stimulated peritoneal macrophages were also added to some tubes. Non-immune macrophages mixed with immunized lymphocytes showed a significantly increased ability to destroy tumour ceils as compared with macrophages in the absence of immunized lymphocytes. The immunized lymphocytes were almost entirely inactive alone. When the number of macrophages was kept constant the cytotoxicity was dependent on the number of viable immunized lymphocytes placed on the target cells. Immunized lymphocytes, in the presence of macrophages, only exhibited strong killing of the target cells against which they had been immunized; some lysis of ‘bystander’ cells was, however, seen provided specific target cells were present. Macrophage monolayers exposed to immunized lymphocytes upon contact with specific antigen became ‘armed’ and showed a significant cytotoxicity for specific target cells. When immunized lymphocytes and normal macrophages were treated with actinomycin D and puromycin, cytotoxicity was inhibited in the immunized lymphocytes but not in the macrophages. The possible mechanism of normal macrophage cooperation with immunized lymphocytes in the cytotoxic killing reaction is discussed. Results presented in this paper favour the view that immunologically specific cytophilic factor (presumptive cytophilic antibody) is involved in the macrophage-mediated cytotoxicity in the system studied. [ABSTRACT FROM AUTHOR]

This study was designed to evaluate the effect of four commercially available dressings (Coe, PPC-Eugenol, PPC-Non Eugenol, and Ward's Wondr Pak) on a monolayer of cells, employing the cell culture assay plate assembly, Monolayers of L929 fibroblasts were grown out on the cell culture assay plates and stained with a vital stain, .01% Neutral Red, 8 mm discs of prepared periodontal dressings, as well as sterile filter paper and high density polyethylene discs, which served as controls, were placed on the monolayer. Observations were made at 1,2,6,8 and 24 hour intervals, and measurements of the toxic zones were recorded. Results indicate that all periodontal dressings tested in this system demonstrated definite cytotoxicity. Both macroscopically and microscopically, the first signs of cell damage and/or death were observed adjacent to Ward's Wondr Pak and PPC-Non Eugenol dressings. Although these two dressings produced the earliest toxic signs, after 24 hours Coe-Pak produced the most extensive zones of destruction, while PPC-Eugenol appeared to be the least toxic. [ABSTRACT FROM AUTHOR]

1. A process of extraction and assay, which combines the features of several existing methods, is described for the lytic materials which can be obtained from blood, plasma, serum, and tissues. At least two alcohol-soluble substances, one ether-soluble ("soap-like") and the other insoluble in ether in the cold ("lysolecithin-like"), can be obtained from preincubated blood, plasma, or serum. The hemolytic activity (or concentration) of the soap-like lysin obtained from blood is greater than that of the lysolecithin-like substance, but for plasma and serum the reverse is true, i.e. the red cells are involved in the production of the soap-like lysin, and probably supply some of it when acted upon by enzymes contained in plasma and serum. Preincubation of the blood or plasma increases the yield of lysin two- or threefold, and small quantities of both soap-like and lysolecithin-like lysins can be obtained from unpreincubated blood or plasma. 2. The soap-like lysins obtained from preincubated mouse liver are some 5 to 15 times as active as, or occur in some 5 to 15 times the concentration of, those obtained from blood or plasma. The lysolecithin-like lysins of preincubated liver are about twice as active as, or occur in about twice as great concentration of, those obtained from blood. Because of the shape of the time-dilution curve for these lysins, the relations between their activities, or concentrations, are often quite different from those which one would anticipate if one were to consider only the times required for the production of hemolysis. 3. Paper chromatography can be used to separate the soap-like and the lysolecithin-like lysins obtainable from small quantities of preincubated mouse liver homogenates or preincubated mouse blood. The presence of lysins is detected by their effect on the red cells of a suspension as it wets the paper. Various technical procedures for separating lytic components and for demonstrating that they move on the paper along with protein components are described. 4. Paper strip electrophoresis can be used to show that the supernatant fluid of a preincubated mouse liver homogenate contains at least two protein components and at least two lytic components, not very closely associated in their electrophoretic behavior. 5. Observations on the physical nature of the alcohol- and ether-soluble lysin point to its having a soap-like character. Its activity, as well as that of the lysolecithin-like lysin, is inhibited by cholesterol, by lecithin, and by various fractions of serum. Some of these effects have been studied quantitatively. The most inhibitory of the protein fractions are those which contain lipoproteins; i.e., II + III and IV + V.

Quinine produces haemolysis of rabbit and human red blood cells in concentrations up to 1 in 700. In a concentration of 1 in 10,000 it increases the degree of haemolysis produced by various haemolytic agents like saponin, bile salts and digitonin in vitro. Quinine when injected intravenously in 35 mg./kg. dose in rabbits increases the susceptibility of red blood cells to the haemolytic action of saponin. Intravascular haemolysis following the administration of quinine is seen in cases of blackwater fever, and on the basis of experimental work described in the paper it is suggested that quinine precipitates these haemolytic episodes by rendering the red blood cells more susceptible to the action of tissue lytic factors.

Removal of the white cells and platelets from suspensions of red cells usually produces substantial reduction in the hemolytic activity of venoms. Guinea pig red cells constitute a notable exception and may be lysed by a direct action of venom. White blood cells and platelets appear to contribute to hemolysis by serving as sources of phosphatides for the formation of lysophosphatides. No correlation could be found between phospholipase activity and direct hemolytic activity of venoms. A recently described method (8) of paper chromatographic separation of phospholipides has been used successfully in part of the work.

The mixed leukocyte reaction (MLR) is impaired in multiple sclerosis and certain arthritides, notably rheumatoid arthritis. The present study shows that this phenomenon is not disease-specific: cells from patients with multiple sclerosis react poorly also with cells from patients with arthritis. A time study of the reaction excludes the possibility of an initial strong MLR followed by cell death -- a phenomenon sometimes seen in animal experiments. A study of the effect of patient sera on a two-way MLR between normal individuals shows that a small depressive effect is present with the patient sera, but this is not of the magnitude that it can explain the MLR impairment under study. [ABSTRACT FROM AUTHOR]

During the late embryonic period, cell death occurs in the central nervous system of Calliphora erythrocephala. The degenerating cells are small and rounded, contain a pyknotic nucleus, and selectively accumulate basic vital dyes such as nile blue sulphate and acridine orange. The number of degenerating cells is highest 13-15 hours after oviposition and decreases during the shortening of the ventral nerve cord. Nevertheless, these degenerating cells do not represent a morphogenetic phenomenon, since their number is too small to account for the 55% decrease in the length of the ventral nerve cord. In all probability the pyknoses seen in the central nervous system of this holometabolic insect are to be interpreted as phylogenetic degenerations of clearly vestigial neuroblasts that have lost functions they might have retained in the larvae of insects in lower orders, for instance the innervation of legs, wings, a larger number of abdominal segments, etc. About half of the pyknoses occur in pairs. [ABSTRACT FROM AUTHOR]

Fourteen days after injection with Detroit-6 cells (a human cell line) rats have high titres of antibody capable of inducing cytotoxicity towards Detroit-6 cells in normal spleen cells. At the same time, the spleen cells from the injected rats are cytotoxic for Detroit-6 cells in vitro. However, killing by allergized spleen cells is apparently not entirely antibody induced, since heterologous anti-thymocyte sera (absorbed with rat bone marrow cells) inhibit target cell killing by spleen cells from injected rats but do not appreciably inhibit killing of antibody-coated target cells by normal spleen cells. Wistar spleen cells 'activated' by transfer into irradiated August rats are cytotoxic for August hepatoma cells. This cytotoxicity is also inhibited by the absorbed anti-thymocyte sera. It is suggested that the cytotoxicity of spleen cells in vitro, in both these allogeneic and xenogeneic systems, is mediated by thymus-derived (T) cells. [ABSTRACT FROM AUTHOR]

The aim of the experiments was to find a T cell-mediated cytotoxic reaction where genetically determined low responsiveness is under the control of recessive genes. The T cell-mediated immune response to DBA/2 mastocytoma cells P 815-X2 in different inbred strains, F1 hybrids and congenic resistant strains of mice was determined using the 51Crk-release method. Two types of low responsiveness were found. The first already well documented type is characterized by dominance of low responsiveness in genetical analysis. It is due to tolerance because of the identity of the H-2 linked specificities of the recipient and of DBA/2 (H-2d) mice from which the turnout is derived. The second and new type of low responsiveness in T cell-mediated immunity was found in DBA/1 mice. In this strain low responsiveness is inherited as a recessive trait. The cytotoxic response of DBA/1J mice against the C57B1/6 lymphoma EL 4 is normal. Thus, their low responsiveness is restricted to a limited number of membrane determinants. [ABSTRACT FROM AUTHOR]

Two major types of cell-mediated cytotoxicity in vitro after alloimmunization in the human have been described--antibody-dependent lymphocyte-mediated cytotoxicity (ADLC) and direct immune-lymphocyte-mediated cytotoxicity (DLC). The characteristics of these two in vitro systems are compared. The cytolysis occurred as a linear function of time in both cases. The effector cell dose response relationship was in both systems well described by a linear correlation between the logarithm of the effector cell dose and the cytotoxic activity. Anti-immunoglobulins inhibited ADLC but not DLC. The reactivity in DLC was potentiated by the addition of isoantibody directed against target cells. [ABSTRACT FROM AUTHOR]

Cell-mediated lysis of target monolayers infected with lymphocytic choriomeningitis virus has previously been shown to be a property of specifically sensitized thymus-derived lymphocytes (T cells). The cytotoxic potential of individual effector lymphocytes is maximally expressed when infected monolayers are confluent and overlaying immune spleen cells cover less than the total target area. The data presented support the following interpretations: [1] Cell-mediated injury depends on close association between sensitized T cells and infected L cells. [2] Any attachment made is readily reversible. [3] Effector lymphocytes may damage more than one target cell, operating, perhaps, in a rather circumscribed area. [4] Cell death is a 'one hit' phenomenon. [5] Cytolysis is a property of individual T cells, there being no obvious requirement for co-operation between different populations of spleen cells. [6] Substances secreted into the medium at large are neither directly cytotoxic nor capable of sensitizing normal spleen cells. [7] Specific lysis occurs at temperatures ranging from 27°C to 40°C, being maximal at the higher temperature. [ABSTRACT FROM AUTHOR]

Zones of cell death in the chick embryo heart were demonstrated by a study of cardiac morphogenesis on the light microscopical level. Between the 2nd and 20th day of incubation 31 foci of cell degeneration were found. The greatest number of dying cells occured on the 4th day of incubation and was located in the heart bulbus and bulbar cushions. The largest number of different degenerative foci were present on the 6th incubation day. Starting on the 10th day of incubation, both the number of degeneration zones and their population of dying cells decreased. [ABSTRACT FROM AUTHOR]

A method for the quantitation of cytotoxic action of antiserum and complement is described, measuring the incorporation of trypan blue into Ehrlich ascites tumour cells. The incorporation of the dye into the cells in the presence of antiserum and complement was maximum at ionic strength between 010 and 015, and decreased with increasing ionic strength higher than 015. The permeability barrier of the cell against the dye was stable at pH between 7.2 and 7.4. The cytotoxic reaction required Mg ++ and Ca++ ion, but was inhibited with concentrations higher than 5 mM Mg+ + and 1 M NCa. The incorporation of the dye in the presence of antiserum and complement was more rapid with increasing concentrations of the dye, and depended on temperature. From these findings we obtained optimal condition for the assay of cytotoxic antiserum. [ABSTRACT FROM AUTHOR]

Experiments are described using the reactive lysis system on phospho-lipid dispersions to study the terminal phases of complement lysis. It has been found that, both on lecithin and on sphingomyelin-cholesterol liposomes, marker release and characteristic EM lesions can be found upon the sequential activity of C567 and C8 and C9 and that for both these parameters of lysis the action of C8 and C9 as well as of C567, are required. Lysis of liposomes is accompanied by the appearance of traces of the products of phospholipase activity in the supernate but it is believed that these represent the activity of contaminating enzymes and are the consequence and not the cause of lysis. However the possibility that lysis could be due to lipolytic activity cannot be totally excluded because of the negligible hydrolysis theoretically needed to form lesions. [ABSTRACT FROM AUTHOR]

The removal of the horny layer of the guinea-pig ear by tape stripping causes rapid development of a parakeratotic scale during the first 12 hr. Some epidermal cells, which were labelled with ³H-Thymidine when stripping was performed, could be detected autoradiographically in the parakeratotic stratum corneum a few hours litter. Since the proliferative response of the epidermis is retarded after vigorous stripping, these cells have become parakeratotic due to exposure and subsequent cell death. Topical application of Vitamin A-acid produces morphological alterations of the keratogenous zone together with increased DNA-synthesis in the lower portion of the epidermis, leading to the persistence of nuclei in the stratum corneum. Prolonged treatment with Vitamin A-acid and Hexadecane increases the epidermal thickness to values such as are found in psoriasis. The turnover time of this hyperplastic epidermis is reduced to about 3 days, yet no parakeratosis can be found. These observations lead to the conclusion that maximally stimulated epidermopoiesis does not result in parakeratosis unless there is a defect in cell differentiation. [ABSTRACT FROM AUTHOR]

This article focuses on a study related to the direction of growth of epithelium. A constantly recurring theme in the literature devoted to dermatology is that the epidermis moves outwards. Researchers estimated the magnitude of the cellular production by assessing the number of mitoses present in the epithelium of tile crypts and by comparing this figure with the total number of cells present in both crypts and villi. They found that the epithelium of the crypts in the duodenum and ileum of adult rats showed an unusually large number of cells undergoing mitosis and they postulated that since the balance of cell death versus production depended on loss visible only at the tips of the villi, cells formed in the crypts must move upward along the side of the villi to be ejected when they reach the tips of the latter.

The palatine process epitheliums of rat and mouse embyros were studied in various stages of fusion to determine the origin of cell death in the fusion line, and the amount of adhesion opposing palatine processes. [ABSTRACT FROM AUTHOR]