The cytotoxic action of immune gamma globulin and complement on Krebs ascites tumor cells. I. Ultrastructural studies

A calcium optimum for cytotoxic T lymphocyte and natural killer cell cytotoxicity

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells are required for host defense. They destroy malignant target cells like cancer cells. Among metal cations, Ca²⁺ plays a prescinded role for CTL and NK cytotoxicity as it is the only cation used as ubiquitous second messenger. Measuring intracellular Ca²⁺ concentrations [Ca²⁺]_int in single cells has greatly changed our understanding of Ca²⁺ signaling. Yet, comparing the role of Ca²⁺ in the pre-[Ca²⁺]_int and [Ca²⁺]_int measurement era reveals that even in the pre-[Ca²⁺]_int measurement era (before 1980), the functions of Ca²⁺ and some other metal cations for the cytotoxic immune response were well established. It was even shown that Ca²⁺ influx across the plasma membrane but not Ca²⁺ release from intracellular sources is relevant for lymphocyte cytotoxicity and that very little Ca²⁺ is needed for efficient lymphocyte cytotoxicity against cancer cells. In the [Ca²⁺]_int measurement era after 1980, many of the important findings were better and more quantitatively refined and in addition the molecules important for Ca²⁺ transport were defined. The unexpected finding that there is a Ca²⁺ optimum of CTL and NK cell cytotoxicity deserves some attention and may be important for anti-cancer therapy.

Complement C5b-9 and Cancer: Mechanisms of Cell Damage, Cancer Counteractions, and Approaches for Intervention

The interactions of cancer cells with components of the complement system are highly complex, leading to an outcome that is either favorable or detrimental to cancer cells. Currently, we perceive only the "tip of the iceberg" of these interactions. In this review, we focus on the complement terminal C5b-9 complex, known also as the complement membrane attack complex (MAC) and discuss the complexity of its interaction with cancer cells, starting with a discussion of its proposed mode of action in mediating cell death, and continuing with a portrayal of the strategies of evasion exhibited by cancer cells, and closing with a proposal of treatment approaches targeted at evasion strategies. Upon intense complement activation and membrane insertion of sufficient C5b-9 complexes, the afflicted cells undergo regulated necrotic cell death with characteristic damage to intracellular organelles, including mitochondria, and perforation of the plasma membrane. Several pro-lytic factors have been proposed, including elevated intracellular calcium ion concentrations and activated JNK, Bid, RIPK1, RIPK3, and MLKL; however, further research is required to fully characterize the effective cell death signals activated by the C5b-9 complexes. Cancer cells over-express a multitude of protective measures which either block complement activation, thus reducing the number of membrane-inserted C5b-9 complexes, or facilitate the elimination of C5b-9 from the cell surface. Concomitantly, cancer cells activate several protective pathways that counteract the death signals. Blockage of complement activation is mediated by the complement membrane regulatory proteins CD46, CD55, and CD59 and by soluble complement regulators, by proteases that cleave complement proteins and by protein kinases, like CK2, which phosphorylate complement proteins. C5b-9 elimination and inhibition of cell death signals are mediated by caveolin and dynamin, by Hsp70 and Hsp90, by the mitochondrial stress protein mortalin, and by the protein kinases PKC and ERK. It is conceivable that various cancers and cancers at different stages of development will utilize distinct patterns of these and other MAC resistance strategies. In order to enhance the impact of antibody-based therapy on cancer, novel precise reagents that block the most effective protective strategies will have to be designed and applied as adjuvants to the therapeutic antibodies.

Suppression of injuries caused by a lytic RNA virus (mengovirus) and their uncoupling from viral reproduction by mutual cell/virus disarmament

Viruses often elicit cell injury (cytopathic effect [CPE]), a major cause of viral diseases. CPE is usually considered to be a prerequisite for and/or consequence of efficient viral growth. Recently, we proposed that viral CPE may largely be due to host defensive and viral antidefensive activities. This study aimed to check the validity of this proposal by using as a model HeLa cells infected with mengovirus (MV). As we showed previously, infection of these cells with wild-type MV resulted in necrosis, whereas a mutant with incapacitated antidefensive ("security") viral leader (L) protein induced apoptosis. Here, we showed that several major morphological and biochemical signs of CPE (e.g., alterations in cellular and nuclear shape, plasma membrane, cytoskeleton, chromatin, and metabolic activity) in cells infected with L(-) mutants in the presence of an apoptosis inhibitor were strongly suppressed or delayed for long after completion of viral reproduction. These facts demonstrate that the efficient reproduction of a lytic virus may not directly require development of at least some pathological alterations normally accompanying infection. They also imply that L protein is involved in the control of many apparently unrelated functions. The results also suggest that the virus-activated program with competing necrotic and apoptotic branches is host encoded, with the choice between apoptosis and necrosis depending on a variety of intrinsic and extrinsic conditions. Implementation of this defensive suicidal program could be uncoupled from the viral reproduction. The possibility of such uncoupling has significant implications for the pathogenesis and treatment of viral diseases.

The cytotoxic action of immune gamma globulin and complement on Krebs ascites tumor cells. II. Chemical studies

The in vitro exposure of Krebs ascites tumor cells to the action of rabbit immune gamma globulin alone does not result in any changes in the cell concentration of amino acids, ribonucleotides, RNA, DNA, or protein, nor in the rate of entry of potassium into the cell. The exposure of the cells to antibody + complement results in the following changes within a few minutes:— (a) Loss of about two-thirds of the free amino acids and ribonucleotides. (b) Loss of about 90 per cent of the intracellular potassium. (c) Loss of about three-quarters of the cell RNA to the medium, part appearing as TCA-soluble and the rest as TCA-insoluble products. There were no changes detectable in DNA. (d) A small increase in total free amino acid of the cell suspension. (e) Loss of from 30 to 60 per cent of the cell protein. The loss of these substances is believed to occur through a cell membrane which is still intact, as judged by phase and electron microscopy, and still able to discriminate to a small degree against passage of larger molecules.

Structural changes in mammalian cells associated with cooling to-79 degree C

Suspensions of HeLa and S37 cells, with and without added glycerol, were cooled in stages to -79°C. and held at that temperature for 30 minutes. After warming to room temperature the cells were fixed, sectioned, and compared by phase contrast and electron microscopy with similar specimens kept at room temperature. Correlated viability tests were made. Abnormal cytological characteristics, visible with the phase contrast microscope, were clearly related to the sequence of freezing and thawing, and the proportion of altered cells was highest in specimens cooled without glycerol. Electron microscopy showed that even in the presence of glycerol all cells were markedly altered, with distinctive vesiculation and disruption of the various intracellular membranes. There is evidence that much cytoplasmic damage is compatible with survival, but it seems likely that separation of the two layers of the nuclear envelope and rearrangement of the nuclear contents are signs of irreversible damage. The findings lend some support to the belief that cell death on cooling is due largely to denaturation of semipermeable membranes, caused by the increasing concentration of electrolytes.

Immune cytolysis: electron microscopic localization of cellular antigens with ferritin-antibody conjugates

Immune gamma globulin has been coupled to ferritin by the diisocyanate method of Singer. The final product ("ferroglobulin") had approximately 13 per cent of its gamma globulin coupled to ferritin, and roughly half of its ferritin coupled to gamma globulin. The uncoupled gamma globulin could be removed by ultracentrifugal sedimentation of the free ferritin and the ferritin-antibody conjugates. The characteristics of the native antibody were retained by the ferritin-antibody conjugates, for they could be precipitated by anti-gamma globulin antisera, and when used as antibodies, they reacted specifically with soluble and cellular antigens. Ferroglobulin preparations made from rabbit antisera against whole ascites tumor cells were incubated with the cells, and the location of ferritin determined by electron microscopy of thin-sectioned material. It was found that the immune ferroglobulins localized specifically on antigens of the cell membrane. Some of the ferritin label entered the cells by pinocytosis, but the ferritin-antibody units did not appear able to pass directly through the cell membrane into the cytoplasmic matrix. When cells were incubated with ferritin-labeled antibody and complement, antibody could be located in the cytoplasmic matrix, and it therefore appeared that complement action was required before antibody could pass directly through the cell membrane. This finding was consistent with previous observations that the plasma membrane of an antibody-complement treated cell becomes permeable to large molecules. In broken cell preparations incubated with ferroglobulin, antibody combined with amorphous material and with structures derived from cell membranes and from smooth membranes of the endoplasmic reticulum. The data favor the concept that antigens contained within the membranous structures are most important in the formation of cytotoxic antibodies. The reported experiments support the view that cytotoxic antibodies fix primarily to surface antigens of the cell membrane. The subsequent action of complement establishes the permeability defect that induces the osmotic lysis of the cell and permits antibody to pass into the cell where it may act in a similar fashion on intracellular organelles.

Chromatographic resolution of the first component of human complement into three activities

A euglobulin fraction of human C'1 has been chromatographically resolved into three distinct activities, designated C'1q, C'1r, and C'1s, in the order of their elution from DEAE cellulose. All three of these activities have been shown to participate in various hemolytic reactions requiring C'1, including the cold phase of the Donath-Landsteiner reaction, and to be necessary for generation of C'1 esterase. C'1q was identical with a previously described serum protein implicated in a very early step of complement action and designated the 11S component on the basis of its sedimentation constant. C'1r could not be related to a known complement activity and has been presented as a new component. C'1s, on the basis of chromatographic evidence, was identified with C'1 proesterase. Methods of assay of these components of C'1 have been presented. The significance of C'1q, C'1r, and C'1s in generation of C'1 esterase and the central role of this enzyme in reactions involving C'1, C'4, and C'2 have been discussed.

Immune cytolysis. 1. The release of ribonucleoprotein particles. 2. Membrane-bounded structures arising during cell fragmentation

It has been shown that Krebs ascites tumor cells incubated in vitro with immune gamma globulin and complement lose the bulk of their cytoplasmic RNA to the suspending medium, although the cell membrane remains visibly intact. The present experiments show that about four-fifths of the lost RNA is sedimented by centrifugation of the cell-free medium at 105,000 g. Electron microscopic and chemical analyses of the pellets show them to consist of 150 A ribonucleoprotein particles. It is concluded that most of the RNA passes from the cells in this form. Antibody-complement action causes osmotic swelling of the tumor cells and they become quite fragile. Fragmentation of such preparations yields large numbers of membrane-bounded spheres which may be separated from the heavier nuclei by differential centrifugation. Electron microscopic study of the spheres provides evidence that they can arise from segments of the cell surface as well as from mitochondria and the endoplasmic reticulum.

Studies on immune cellular injury. I. Cytotoxic effects of antibody and complement

A model system for the investigation of immune cellular injury in primary isolates of a fixed-tissue cell of human origin has been described, using metabolism-inhibition and uptake of trypan blue as independent criteria of cytoxicity. Cytotoxic effects on human amnion cells were produced by the combination of specific rabbit antibody and factors in normal human serum which were indistinguishable from the components of hemolytic complement and calcium and magnesium ions. The data have been discussed in relation to the apparent multiplicity of serologic systems which can effect cellular injury. The nature of the cell and the source of antibody or normal serum constituents have been emphasized as factors which may influence the experimental selection of a given humoral mechanism.

Effect of antibody and complement on permeability control in ascites tumor cells and erythrocytes

Rabbit antibody + complement alters the permeability properties of mouse Krebs ascites tumor cells and erythrocytes. When antibody + C' acts on ascites tumor cells in a low protein medium, intracellular K⁺ is lost from the cells at a rate far greater than the normal leak rate. At the same time the cells lose amino acids and ribonucleotides and become fully permeable to the Na⁺ of the medium. When antibody + C' acts in a low protein medium, the cells swell extensively and lose most of their macromolecules to the medium (hemoglobin from erythrocytes, protein and RNA from the ascites tumor cells). If the antibody + C' acts in a medium containing protein in sufficient concentration to balance the colloid osmotic pressure of the cells, the swelling is prevented; no macromolecules are then lost from the cells, but the loss of K⁺ and entrance of Na⁺ are not altered, and the loss of amino acids and ribonucleotides is only slightly affected. It therefore appears that the action of antibody + C' is to produce functional "holes" in the animal cell membrane which permit the equilibration of cations and small molecules between cell and medium. This leads to an increase in the osmotic pressure of the cell and a rapid influx of water. The cell membrane and its "holes" are thereby stretched, permitting macromolecules to escape from the cell.

Histopathological and histochemical alterations in the early stages of corneal graft rejection

Rejection of corneal grafts was produced in rabbits after skin from the corneal donor was grafted subcutaneously. Clinical observations showed that the graft sickness started at the periphery of the graft after blood vessels from the host cornea reached the scar. Histologic studies demonstrated that the scar tissue was first invaded by vessels and infiltrated by lymphocytes, monocytes, and plasma cells. This infiltrate reached the endothelium through the gap in Descemet's membrane. The early histological picture of the graft sickness was characterized by endothelial destruction and infiltration at its junction with the scar. Keratocytes changed in shape and apparently became active fibroblasts. Decreased amounts of ground substance in the early stages of rejection, as indicated by appearance of haziness in the graft, were indicated in sections by a decrease in metachromatic staining. Diminished uptake of radioactive sulfate also occurred in the early stages of the graft sickness; which was followed by an elevated uptake of sulfate as the graft became opaque and filled with active fibroblasts.

IMMUNO-ELECTRON MICROSCOPE ANALYSIS OF THE SURFACE LAYERS OF THE UNFERTILISED SEA URCHIN EGG. I. EFFECTS OF THE ANTISERA ON THE CELL ULTRASTRUCTURE

The response of unfertilised Paracentrotus lividus eggs to γ-globulin fractions of antisera against isolated homologous jelly coat substance or homologous homogenates of jellyless eggs has been studied at the ultrastructural level. The antijelly γ-globulin caused precipitation of the jelly layer, the density of precipitation varying between different eggs and being proportional to the γ-globulin concentration. Agglutination of the jelly substance of adjacent eggs, which is species specific, occurred frequently with higher γ-globulin concentrations. Antiegg γ-globulins (from antiserum against total homogenates of jelly-free eggs or the heat-stable fraction thereof) did not produce these effects. Instead, these γ-globulins caused various structural alterations mostly representing stages in parthenogenetic activation. This species-specific activation was induced by the reaction of antibodies with some heat-stable egg antigens different from those involved in jelly precipitation. Surface alterations included the formation of small papillae, membrane blisters, hyaline layer, and activation membrane, the release of material from the cell surface, and the breakdown of cortical granules. These alterations were dependent on both γ-globulin concentration and the variable reactivity among different females. Aster formation, found intracellularly, verified that the surface responses represented real parthenogenetic activation and were not the result of immune lysis. No such alterations appeared in the controls.

EFFECTS OF ANTICELLULAR SERUM ON PHAGOCYTOSIS AND THE UPTAKE OF TRITIATED THYMIDINE AND URIDINE BY HELA CELLS

Anticellular serum inhibited phagocytosis of colloidal gold and staphylococci by HeLa cells. This inhibition of phagocytosis was reversed by conditions which allowed the antibody to elute from the cell. Concentrations of antiserum that inhibited phagocytosis did not interfere with the transport of tritiated thymidine and uridine across the cell membrane, and their incorporation into cell nucleic acids was unaltered as evaluated by autoradiography. These results indicate that thymidine and uridine were taken into cells independently of phagocytosis. Morphologic changes induced in the cells by antibody suggest that the antibody agglutinates adjacent portions of the cell membrane. This agglutination of the cell membrane by antibody would be expected to interfere with the continuous evagination and invagination of the cell membrane associated with phagocytosis. The inhibition of virus infection by anticellular antibody may be a result of the effect of the antiserum upon phagocytosis.

ANTISERUM TO LEUCOCYTE LYSOSOMES. ITS CYTOTOXIC, GRANULOLYTIC, AND HEMOLYTIC ACTIVITIES

Antisera to rabbit polymorph granules and to rabbit erythrocytes have been prepared in guinea pigs. Both antigranule and antierythrocyte sera are hemolytic and both exhibit striking cytotoxicity on leucocytes. The sequence of toxic events, as observed by phase contrast cinemicrophotography and electron microscopy, consists of explosive granule lysis, cell swelling, cytoplasmic liquifaction, and nuclear fusion. Other rabbit cells are also susceptible to these cytotoxic effects, but cells, including polymorphs, of other mammals are not. Cytotoxic action of the antisera requires, in addition to the antibody, heat-labile serum factors and divalent cations, suggesting that the action is a combined one of antibody and complement. The morphologic observations have been supported by biochemical studies demonstrating release into the medium of granule-bound hydrolases following exposure of polymorphs or of isolated granules to the antigranule or antierythrocyte sera. Granulolytic activity of the antisera can be reduced or removed by absorption with either rabbit leucocyte granules or with erythrocytes, indicating that leucocyte granules and erythrocytes have an identical or similar membrane constituent. The observations lend support to the notion that lysosomal hydrolases may exert autolytic effects in some situations.

IMMUNO-ELECTRON MICROSCOPE ANALYSIS OF THE SURFACE LAYERS OF THE UNFERTILISED SEA URCHIN EGG. II. LOCALISATION OF SURFACE ANTIGENS

The immunological properties of the surface layers of Paracentrotus lividus eggs have been studied further by using ferritin-labelled antibody to localise specific antigenic sites. In order to detect a wider spectrum of antigenic determinants, several antisera against egg and jelly substance have been employed in combination with absorption procedures using lyophilised antigen. This use of absorbed antisera was made feasible by adding ferritin label in a second antiserum layer of ferritin-anti-γ-globulin. Eggs were treated with antibody for short periods to detect antigenic sites without incurring structural changes (shown in previous paper) resulting from long antibody treatment. Unspecific ferritin uptake, found in pinocytotic vesicles and yolk granules, is considered in relation to yolk formation. The jelly layer, found to be immunologically heterogeneous, included one component interacting with antijelly γ-globulin and one with antiegg γ-globulin. The vitelline membrane proved to be rich in egg antigens (heat-stable and heat-labile). The role of this layer in specificity of fertilisation, parthenogenetic activation, and the possibility of being analogous to a basement membrane are discussed. Few antigenic sites were found on the plasma membrane with antiegg γ-globulin. This γ-globulin resulted in some specific labelling of cortical granules and its action is considered in relation to the permeability properties of the egg.

Complement membrane attack on nucleated cells: resistance, recovery and non-lethal effects

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MHC-specific cytotoxic T lymphocyte killing of dissociated sympathetic neuronal cultures

Experiments were conducted to determine whether neurons in culture can serve as targets for immunologic attack mediated by major histocompatibility complex (MHC)-specific cytotoxic T lymphocytes (CTLs) which recognize Class I antigens. Allogeneic C3H/He primary neuronal cultures were quickly destroyed after CTL addition, while syngeneic C57BL/6J neurons were not lysed. Alterations in the distribution of chromatin were the first ultrastructural changes that occurred, followed by loss of nuclear morphology, cytosolic changes, and eventually fragmentation of both the nucleus and cytosol. With Campenot chambers, it was possible to separate the membrane and nuclear lesions. CTLs exposed to neurites, but separated from the cell body by the chamber barrier, caused degeneration of neurites but did not cause lysis and cell death. Neuronal lysis mediated by antibody and complement appeared to be distinct from CTL-mediated lysis. These experiments demonstrate that neurons in culture are targets for MHC-specific CTLs, and therefore probably express functional levels of Class I antigens. The signal for killing by CTLs is not retrogradely transported from the neurite to the cell body, and morphologic events following CTL-neuron interaction resemble those that occur in dividing tumor target cell populations.

Apoptosis, lymphocytotoxicity and the containment of viral infections

It is generally agreed that cellular immunity plays an important role in limiting certain primary viral infections. Morphological studies indicate that cell death induced by T cells, K cells and NK cells takes the form of apoptosis, not classical necrosis. Killing of a virus-infected cell by either of these means prior to the assembly of infectious virus would clearly contain the infection. Our hypothesis is that the exclusive involvement of apoptosis in lymphocytotoxicity may have additional advantages in preventing virus dissemination. Firstly, a very early event in apoptosis is activation of endogenous, non-lysosomal endonuclease, and this might destroy virus. Secondly, apoptosis results in the formation of membrane-bounded cell fragments, which are phagocytosed intact and digested within the lysosomes of adjacent cells. In contrast, necrosis is characteristically associated with rupture of the cell membrane and release of cellular contents; its induction by non-budding viruses aids in spread of the infection.

Evidence for complement-induced endothelial injury in vivo: a comparative ultrastructural tracer study in a controlled model of hyperacute rat cardiac allograft rejection

In order to delineate the potential role of platelet-derived factors and of the direct lytic action of complement in the pathogenesis of endothelial injury in hyperacute allograft rejection, a highly reproducible and rigidly controlled inbred rat cardiac model was studied, utilizing colloidal carbon as a vascular tracer for comparative ultrastructural analysis of the microcirculation. Unmodified allografts were characterized by widespread intramural carbon labeling of the microvasculature, which corresponded to sites of platelet sequestration and extensive endothelial cell disintegration. Under conditions of recipient platelet depletion without concomitant complement depression, carbon-labeled segments of the microcirculation showed widespread endothelial cell disintegration, the ultrastructural features of which were similar to those observed in the unmodified allograft group. The microvasculature of syngeneic heart grafts transplanted to platelet-depleted recipients as well as all platelet-depleted recipients' own hearts showed no similar ultrastructural changes. It is thus concluded that the loss of cellular integrity of the microcirculatory endothelium in hyperacute rat cardiac allograft rejection is not a platelet-dependent phenomenon. The current ultrastructural data combined with previous morphologic studies provide strong evidence that the severe form of endothelial injury observed in this model is mediated by the direct action of activated complement components.

Scanning and transmission electron microscopic studies of complement-mediated lysis and antibody-dependent cell-mediated cytolysis of herpes simplex virus-infected human fibroblasts

The morphologic aspects of complement-mediated and antibody-dependent cell-mediated cytolysis (ADCC) of human fibroblasts (HuFs) infected by herpes simplex virus (HSV) is described. Human antiviral antibody (antiHSV) was shown by transmission and scanning electron microscopy (TEM and SEM) to cause the deposition of an amorphous material over the surface of infected cells and virus particles. Associated with antiHSV treatment, the HuFs underwent endocytosis, with the appearance of pinocytotic vesicles immediately beneath the plasma membrane. The addition of complement resulted in lysis of the infected HuFs and massive dilatation of the perinuclear cisternae, but the virus particles associated with the cell surface did not appear lysed. Instead, an additional deposit was noted on the enveloped particles after the addition of complement (C). Human peripheral blood mononuclear leukocytes (MNLs) also lysed the antibody-coated, infected HuFs. Lymphocytes formed broad-based areas of attachment to the antiHSV-treated cells. Beneath these areas of contact occurred focal cytoplasmic changes that preceded cell lysis. Monocytes showed multiple points of binding and sent cytoplasmic projections over the surface of the infected HuFs. Virus particles and segments of target cell cytoplasm were gathered into vacuoles of the monocyte. In accord with the above morphologic findings, the relative roles that antibody, C, and leukocytes may play in human viral diseases is discussed.

Dependence on antigen dose and timing in the immune response of C3H mice to malignant ascites cells

This study presents evidence suggesting that the immune response to malignant ascites cells exists in some state of balance, which seems to be regulated by the dose of antigen and the time used for immunization. Injection s.c. of high doses of tumour cells weekly for 5 weeks afforded protection against a subsequent i.p. tumour graft. Immunization by the same route with a 100-fold lesser amount of the tumour also induced immunity, but along with factors able to abrogate the effect of this immunity. These tumour-specific factors were able to reduce the binding to the cell membrane of specific antibodies detectable in the indirect immunofluorescence test and to protect the tumour cells against complement-dependent cytotoxic activity present in the tumour fluid. The factors interacted with protein A at pH 8.0, suggesting that they share properties with immunoglobulins. The factors eluted in the same fractions as IgG from Sephadex G-200 and showed high affinity for membrane associated antigens.

Experimental immune pancreatitis in the mouse by rabbit immune sera directed against purified enzymes of the exocrine pancreas

An experimental xenogeneic immune pancreatitis was induced in AB-mice by repeated intraperitoneal injections of rabbit immune sera directed against purified pancreatic enzymes (alpha-amylase, lipase, trypsin) for 3 hours up to 8 days. Histologically, the immune pancreatitis is characterized by three different findings: 1. Multiple acinar cell necroses on the 2nd, 3rd and 5th day of immune serum application. 2. A dedifferentiating acinar cell atrophy with development of pseudocanalicular acini on the 5th and 9th day. 3. An increasing interstitial histiolymphoplasmocytic pancreatitis on the 5th and 9th experimental day. Ultrastructurally, the acinar cell necroses proved as the final stage of a step-by-step developing acute lethal cell damage. The dedifferentiating acinar cell atrophy corresponds to a chronic sublethal cell injury with alteration of different cytoplasmic components. The interstitial pancreatitis in immune serum treatment is characterized by differently activated histiocytes and lymphocytes as well as by mature plasma cells. Because of immune histological findings (peri- and intraacinar deposition of rabbit globulin, specific fixation of guinea-pig complement, and appearance of mouse globulin in the mouse exocrine pancreas) and control experiments with rabbit and mouse normal serum as well as with physiological saline, the pathogenesis of the induced xenogeneic immune pancreatitis is regarded as a twophase process: 1. The acinar cell necroses are mainly due to a cytotoxic immune reaction (possibly in combination with an immune complex reaction) caused by specific anti-pancreatic enzyme antibodies of the applied immune sera. The dedifferentiating acinar cell atrophy may be the result of a specific action of the anti-enzyme antibodies against the corresponding pancreatic enzymes in the apical secretion granules of the pancreatic acinar cells. 2. The interstitial histiolymphoplasmocytic pancreatitis is mainly the morphologic substrate of an extravascularly (intraperitoneally) induced serum sickness reaction (immune complex reaction) due to the foreign proteins applied with the xenogeneic immune sera.

Isotope-labelled alpha-amino-isobutyric acid as an indicator in cytotoxicity tests

The effect of rabbit antisera on the uptake and release of alpha-amino-isobutyric acid (AIBA) in LS- and P-388 cells was investigated. In the presence of homologous antiserum and complement, the uptake of AIBA was inhibited. In the absence of complement, no effect of antiserum was seen. Using prelabelled cells, the efflux of AIBA was greatly accelerated in the presence of antiserum and complement. The AIBA-uptake method was compared with the trypan blue exclusion test and the 51Cr release technique. The AIBA-uptake method was more sensitive in quantitative cytotoxic studies.

DEAE-dextran and polybrene cation inhibition of antibody/complement mediated in vitro immune haemolysis

Preincubation of unsensitized sheep erythrocytes with 25 mug/ml of the polycations DEAE-dextran or polybrene prevented immune haemolysis. This inhibition could be reversed by polyanion. When already sensitized cells were incubated in polycation or when polycation was added to complement, less effect was found on haemolysis. Cell electrophoresis and immunoelectrophoresis showed that polycation does not prevent attachment of antibody to the cells.

Successful short-term modification of hyperacute renal allograft rejection in the primate. Intrarenal effects of phenoxybenzamine and methylprednisolone combined with heparin

Inhibition of renal vasoconstriction during hyperacute rejection by phenoxybenzamine or methylprednisolone combined with either the antiplatelet agent pyridinolcarbamate or heparin was evaluted in primates. Phenoxybenzamine plus pyridinolcarbamate did not prolong kidney survival. Phenoxybenzamine plus heparin uniformly prolonged low rates of venous flow to 180 minutes and delayed secondary C3 consumption, sequestration of erythrocytes and platelets, coagulation, and fibrinolysis; neutrophil sequestration and vascular injury and obstruction were more marked than with heparin alone. Host pretreatment with methylprednisolone plus heparin also prolonged the low rates of venous flow to 180 minutes, further reduced secondary alterations, and resulted in the least vascular injury. When intact donor kidneys were also pretreated with methylprednisolone, persistently normal rates of venous flow were achieved. Despite marked consumption of Factor XII, the consumption of C3, other coagulation factors, prekallikrein, and sequestration of formed elements was minimal, and the histology appeared compatible with even more prolonged survival.

The "no-reflow" phenomenon after temporary coronary occlusion in the dog

The role of microvascular damage in the genesis of the "no-reflow" phenomenon was investigated in the left ventricular myocardium of dogs subjected to temporary occlusions of a major coronary artery for 40 and 90 min. Intravenous carbon black or thioflavin S (a fluorescent vital stain for endothelium) were used to demonstrate the distribution of coronary arterial flow in control and damaged myocardium. These tracers were injected simultaneously with release of the coronary occlusion or after 5 or 20 min of reflow of coronary arterial blood. After 40 min of ischemia plus arterial reperfusion, usually the tracers were evenly distributed throughout the damaged tissue at each time of reperfusion. On the other hand, when reflow was allowed after 90 min of ischemia, portions of the inner half of damaged myocardium were not penetrated by the tracers. Electron microscopic study of this poorly perfused tissue revealed severe capillary damage; endothelial cells with large intraluminal protrusions and decreased pinocytic vesicles were common. Also, occasional intraluminal fibrin thrombi were noted, as well as extravascular fibrin deposits and erythrocytes. Myocardial cells were swollen in both poorly perfused and well-perfused irreversibly injured tissue. Contraction bands and mitochondrial Ca(2+) accumulation were prominent features of irreversible injury with reflow at 40 min but were not noted after 90 min of ischemia in areas with poor perfusion. These results suggest that 40 min of ischemia were tolerated by the capillary bed of the dog heart without serious capillary damage or perfusion defects, but that 90 min of ischemic injury was associated with the "no-reflow" phenomenon, i.e., failure to achieve uniform reperfusion. This failure of reflow was associated with extensive capillary damage and myocardial cell swelling. Death of severely ischemic myocardial cells in this model occurs before the onset of capillary damage and the no-reflow phenomenon.

The role of cellular swelling in the pathogenesis of organ ischemia

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Studies on gonococcus infection. II. Freeze-fracture, freeze-etch studies on gonocci

Gonococci have been studied by electron microscopy after freeze-cleavage, freeze-etching and the findings correlated with those obtainable through thin sectioning and negative staining. The outer membrane of the cell wall is composed of round to hexagonal subunits 80 A in diameter. This membrane is also punctuated by 80-A holes visible on the exterior of the organism and extending into the substance or through the outer membrane. Pili coursing over the surface of the organisms appear to maintain a close anatomical relationship with the cell wall. In some instances, the surfaces of the organisms are virtually covered by a layer of pili.