Endogenous factors responsible for leucocytic emigration in vivo

Multiparticle adhesive dynamics: hydrodynamic recruitment of rolling leukocytes

The slow rolling motion of leukocytes along the walls of blood vessels mediated by specific receptor-ligand adhesion is important in inflammation and occurs in postcapillary venules over a wide range of wall shear stresses and vessel diameters. The ability of hydrodynamic collisions between cells to induce capture of free-stream leukocytes to a selectin-bearing surface under shear flow was studied experimentally by using a cell-free assay. It was found that carbohydrate-coated spherical beads, representing model leukocytes, tend to attach to the adhesive wall 4-5 cell diameters up- or downstream of a slowly rolling or stationary adhesive bead. A key feature of such "hydrodynamic recruitment" is that only glancing, indirect collisions occurring close to the plane will result in downstream attachment. A direct numerical simulation of cell capture and rolling that includes multiparticle hydrodynamic interactions is shown to reproduce the observed behavior accurately. The theory predicts that hydrodynamic recruitment will occur in the absence of buoyancy effects and over a range of shear rates, suggesting that the mechanism may be important in vivo. This theory is supported by measurements of leukocyte capture in vivo using the hamster cheek pouch model.

PATHOGENESIS OF INFLAMMATION. I. THE PRODUCTION OF AN INFLAMMATORY SUBSTANCE FROM RABBIT GRANULOCYTES IN VITRO AND ITS RELATIONSHIP TO LEUCOCYTE PYROGEN

Material obtained from the in vitro incubation of granulocytes from saline-induced peritoneal exudates of rabbits has been shown to produce inflammation and fever in rabbits. The supernatant material from cells incubated in saline has been termed granulocytic substance (GS) and is heat-labile. Its production is temperature dependent, occurring at 37 degrees C but not at 4 degrees C, requires viable cells, and is inhibited by potassium ions. A similar material is liberated when cells are incubated in a more physiologic medium. Freezing and thawing of granulocytes does not release GS and the active principle cannot be obtained from the incubation of lymphocytes. GS produces a delayed inflammatory response as measured by leucocyte sticking and emigration in the rabbit ear chamber and the leakage of protein-conjugated dye at the site of intradermal injection. The former response can be accurately quantitated by calculation of the inflammatory index from reactions observed in the ear chamber. The inflammatory reaction and the properties of GS distinguish it from a variety of previously described mediators of inflammation, but GS appears to be identical with leucocytic pyrogen. The possible role of GS in delayed and protracted inflammation and its relationship to the pathogenesis of fever are discussed.

PRODUCTION OF INFLAMMATORY CHANGES IN THE MICROCIRCULATION BY CATIONIC PROTEINS EXTRACTED FROM LYSOSOMES

Lysosomal granules of rabbit exudate polymorphonuclear (PMN) leucocytes were isolated and then lysed by freezing-thawing. Topical application of this material to rat and rabbit mesentery produced sticking and emigration of leucocytes, stasis of blood flow, and petechial hemorrhage. The granule-free, supernatant fraction of the homogenized leucocytes failed to produce any of these reactions. Cationic proteins extracted from these granules by weak acid and precipitated by ethanol at concentrations of 20 and 45 per cent, were also tested on heterologous, homologous, and autologous mesenteric vessels. The 20 per cent ethanol-precipitated fraction produced all of the aforementioned injury reactions, whereas the 45 per cent fraction was inactive. The intensity of inflammatory changes produced by the active cationic protein fraction was greater than that produced by lysed whole granules. Both the 20 per cent and 45 per cent ethanol fractions of cationic protein induced clumping of rabbit platelets, in vitro. The 20 per cent ethanol fraction also caused a slight acceleration in rate of swelling of isolated rabbit liver mitochondria. The active material proved to be non-pyrogenic in rabbits. This material exhibited no kinin-like effects when tested on isolated smooth muscle preparations (rabbit aorta and guinea pig ileum). In the rat, the protein produced a transient vasodepression which was inhibited by pretreatment of the animal with an antihistamine. Ultraviolet absorption data and ribose assays showed that the 20 per cent ethanol fraction contained only 4 per cent or less of ribonucleic acid. Upon electrophoresis in starch gel, using acid buffer, this fraction separated into at least three major components which migrated towards the cathode. Precipitation of one of the slowly migrating components by titration of the fraction to pH 10.5 greatly increased the inflammatory activity of the material. The inflammatory basic protein fraction was essentially devoid of acid phosphatase, beta glucuronidase, acid ribonuclease, lysozyme, and catalase activity. The non-inflammatory basic protein fraction contained appreciable quantities of acid ribonuclease and lysozyme. The foregoing data demonstrate that certain of the cationic proteins present in lysosomes of rabbit exudate PMN leucocytes can reproduce one of the cardinal features of the inflammatory response; namely, adhesion and emigration of leucocytes in the microcirculation. These findings offer fresh support for the role of lysosomes in the pathogenesis of tissue injury, and may help to account for the propagation of leucocyte emigration to peak numbers during inflammatory reactions.

Local antibacterial therapy for the management of orthopaedic infections. Pharmacokinetic considerations

Bone infection has long been a formidable foe of orthopaedic surgeons. The standard method of treating osteomyelitis generally consists of irrigation and debridement supplemented by pre- and postoperative antibiotics and intraoperative antimicrobial solutions. In the 1970s, Buchholz introduced the concept of local antibacterial therapy in the form of antibiotic impregnated bone cement to treated infected arthroplasties. From this, antibiotic impregnated beads were developed to treat local infections of bone and soft tissue. The advantage of these beads compared with parenteral therapy is that they deliver a high concentration of antibacterial locally while avoiding high systemic concentrations, thus avoiding adverse effects that are often associated with parenteral antibacterial therapy. Additionally, methylmethacrylate bone cement does not significantly affect the immune response of the body. This makes the use of antibiotic-impregnated polymethylmethacrylate (PMMA) beads highly effective either as an alternative to, or in conjunction with, systemic antibiotic treatment of infected arthroplasties, and localised bone and soft tissue infection. This article explores the indications for the use of local therapy as well as any advantages or disadvantages it may have over systemic antibacterial treatment. Additionally, there are important pharmacokinetic considerations for the optimal use of antibacterial agents in the treatment of osteomyelitis.

Histochemistry of enzymes associated with tissue degradation incident to orthodontic tooth movement

Orthodontic tooth movement in rats was examined by histochemical techniques for some enzymes associated with bone resorption and tissue damage. The maxillary first molar was moved buccally by means of a fixed appliance with predetermined forces for periods of from 10 hours to 6 days. The activities of acid phosphatase and lactate dehydrogenase were higher in cells in the connective tissue of the periodontal membrane (PDM) than in the oral mucosa. A low orthodontic force resulted in an initial redistribution of acid phosphatase-containing cells in the PDM followed by an increased activity of acid phosphatase. The activity of lactate dehydrogenase in the PDM was not affected by low orthodontic forces. The changes in distribution and activity of acid phosphatase and lactate dehydrogenase incident to a high orthodontic force were similar to those seen incident to a low force. However, there was one definite difference. A zone which lacked acid phosphatase activity and lactate dehydrogenase activity developed in the most compressed areas of the PDM. Prostaglandin synthetase activity was found exclusively in the bone marrow and seemed not to be affected by the orthodontic forces. However, some prostaglandin synthetase activity was found in the oral mucosa corresponding to the site of the orthodontic appliance. The adjacent bone surface was covered with cells showing an intense acid phosphatase activity. In the present study the magnitude of the orthodontic force seemed to be a determining factor for the vitality of the PDM but not for the tissue-degradation activity.

Spontaneous abortions and terminations of pregnancy: histological differences

Curettings from eight gravid uteri are compared with material curetted from 2081 uteri after spontaneous abortions. The outstanding feature of the spontaneous material is the decidual polymorph infiltrate. This was absent in seven of the termination specimens. The one case exhibiting a polymorph infiltrate showed other features of degeneration which suggested that a spontaneous abortion may have been developing before termination occurred. This difference between terminated and spontaneously aborted material may provide a basis for elucidating mechanisms in the latter.

Cellular augmentation of polymorphonuclear leukocyte chemotaxis

The density of neutrophils influences the number of cells that will respond to a chemoattractant, endotoxin-activated serium. When fewer than 3 x 10(5) polymorphonuclear leukocytes (PMN) were placed in the top compartment of a modified Boyden chemotaxis chamber, the cellular response was weak. Complete membrane penetration by activated neutrophils rarely was observed. When this number of PMN was exceeded, however, both the number of cells and the percentage of neutrophils responding to the leukoattractant increased. The density of cells required for effective chemotactic response to occur was such that intimate cell-to-cell contact was suggested. This indicated that PMN exerted a kinetic influence upon one another. Extracts of disrupted PMN induced an otherwise insufficient number of neutrophils to respond to the chemotactic stimulus. The active component was isolated in the cytoplasmic fraction (postcentrifugation, 100,000 x g, 60 min) of PMN, but was not present in other subcellular fractions. This cytoplasmic augmentor of chemotaxis (CACh) increased random mobility of neutrophils, but was not, itself, a chemotactic factor. These findings suggest that PMN cooperate in their response to a leukotactic stimulus.

Role of granulocytes in immune complex-induced tissue injuries

Tissue injury of many types may be caused by deposited complexes of antigen and antibody. The circumstances under which the complexes form and deposit often determine the location and type of injury observed: If the complex forms in the circulation, deposition may occur in arterial walls and glomeruli, initiating lesions in those tissues. If the complex forms in the synovial tissues or spaces, then the reaction will develop at that point. Any local source of antigen will initiate these lesions once antibody is formed. If the source of antigen persists, antibody-forming cells soon establish themselves locally as they do in the active Arthus reaction, and injury will become chronic. When the antibody formed is capable of activating complement, polymorphonuclear leukocytes (PMNs, neutrophils) will accumulate, leading to release of injurious constituents. Such is the case in acute glomerulonephritis, arteritis, synovitis, and vasculitis. The ability of complement to attract the PMNs has been demonstrated as an in vitro phenomenon and as a clear possibility in vivo. The requirement of PMNs in the development of the lesions has been demonstrated. The process by which PMNs and other cells (platelets, mast cells, basophils, and macrophages) release injurious constituents is of great interest currently. The exocytosis of their cytoplasmic granules constitutes the major mechanism of release and involves a complicated series of events outlined in this review. The constituents of PMNs capable of injuring tissue in various ways is described, from peptides capable of increasing vascular permeability, to enzymes that indirectly bring more PMNs and other cells into the lesion, to proteolytic enzymes that hydrolyze vital structures in the tissues. These agents were most likely designed to rid the host of invaders; but at times they are unfortunately directed against the host's own tissues.

Edema formation and neutrophil mobilization in the neutropenic rat

The relationship between leucocyte mobilization and edema formation was evaluated in the carrageenan pleurisy model. In normal rats carrageenan was able to mobilize between 80 and 100 million cells per ml of fluid. In neutropenic rats the concentration fell to between 20 and 50 million cells per ml, suggesting the edema formed after carrageenan injection is not directly correlated with cellular mobilization.

Renal homotransplantation in rats. I. Allogeneic recipients

Within 3-6 hr after the reestablishment of the circulation, a characteristic pathology developed in renal homotransplants. Blood monocytes and lymphocytes adhered to large thin-walled vessels of the septa carrying interlobular arteries, traversed their walls, and aggregated in the connective tissue spaces around them. Within 3 days, the number and size of the extravascular cells markedly increased, filling the septa completely and spreading from them centrifugally to occupy the intertubular spaces throughout the cortex. The composition of these aggregates at first was a mixture of lymphocytes and monocytes, and later consisted of large blast cells, macrophages, a few plasma cells, and polymorphonuclear leukocytes. Mitotic activity was seen 2 days after surgery among the large blast cells and increased to a maximal level a day later. Coevally with these changes, the thin-walled septal vessels, intertubular veins and capillaries, and finally, arteries and arterioles, in that order, were damaged. Focal injury of tubules was slight 24 hr after homografting; widespread cortical necrosis had developed 5-7 days later. At no time up to 7 days were concentrations of immunoglobulins detected by fluorescence microscopy in the transplanted kidneys. The morphologic manifestations and temporal sequences of renal homograft destruction suggested that several mechanisms acted synergistically to eliminate the transplant. The initial injury appeared to be the result of an interaction between host lymphoid cells and target endothelium, a phenomenon akin to allogeneic inhibition; followed by spreading ischemia; additional contact injury to tubules; and nonspecific inflammation associated with necrobiotic tissue.