Activation Of Host Defense Mechanisms Research Articles

Surfactant protein D enhances phagocytosis and killing of unencapsulated phase variants of Klebsiella pneumoniae.

Pulmonary surfactant protein D (SP-D) is a collagenous C-type lectin (collectin) that is secreted into the alveoli and distal airways of the lung. We have studied the interactions of SP-D and alveolar macrophages with Klebsiella pneumoniae, a common cause of nosocomial pneumonia. SP-D does not agglutinate encapsulated K. pneumoniae but selectively agglutinates spontaneous, unencapsulated phase variants, such as Klebsiella strain K50-3OF, through interactions with their lipopolysaccharides (LPS). These effects are calcium dependent and inhibited with maltose but not lactose, consistent with involvement of the SP-D carbohydrate recognition domain. Precoating of K50-3OF with SP-D enhances the phagocytosis and killing of these organisms by rat alveolar macrophages in cell culture and stimulates the production of nitric oxide by the NR-8383 rat alveolar macrophage cell line. SP-D similarly enhances the NO response to K50-3OF LPS adsorbed to Latex beads under conditions where soluble LPS or SP-D, or soluble complexes of SP-D and LPS, do not stimulate NO production. Our studies demonstrate that interactions of SP-D with exposed arrays of Klebsiella LPS on a particulate surface can enhance the host defense activities of alveolar macrophages and suggest that activation of macrophages by SP-D requires binding to microorganisms or other particulate ligands. Because unencapsulated phase variants are likely to be responsible for the initial stages of tissue invasion and infection, we speculate that SP-D-mediated agglutination and/or opsonization of K. pneumoniae is an important defense mechanism for this respiratory pathogen in otherwise healthy individuals.

Impairment of Microbial Killing and Superoxide-Producing Activities of Alveolar Macrophages by a Low Level of Ozone.

Male Wistar rats were exposed to 0.2 ppm ozone for up to 14 days, during which alveolar macrophages were collected by pulmonary lavage to assess the effect of ozone on their microbial killing and superoxide-producing activities. For rapid assessment of microbial killing activity, we measured the release of 3H-radioactivity into the supernatant by deoxycholate-lysis of the macrophages that had phagosytosed and killed 3H-uridine-labeled microbes. The killing activity against Escherichia coli and Candida albicans was reduced to 70-80% of control levels on day 3. However, phagocytosis by and the activity of lysosomal enzymes of the macrophages were not impaired. On day 14 the killing activity against E. coli had returned to control levels, whereas that against C. albicans was still reduced. Because active oxygen species plays an important role in microbial killing activity of macrophages, the effects of ozone on respiratory burst and superoxide production were examined. Aliquots of alveolar macrophages were stimulated with phorbol myristate acetate (PMA), opsonized zymosan, or lipopolysaccharide (LPS) plus cytochalasin E (Cyt.E). The respiratory burst, oxygen consumption for rapid superoxide production, was decreased to 60-80% of control levels on day 3. On day 14, the respiratory burst by opsonized zymosan was still 80% reduced, whereas that by PMA or LPS plus Cyt. E had returned to control levels. In addition, the superoxide-producing activity of ozone-exposed macrophages was 10-60% decreased on day 3. On day 14, the superoxide production by stimulation with opsonized zymosan was still 60% reduced, whereas that by PMA or LPS plus Cyt. E had returned to control levels. In conclusion, because of their decreased production of superoxide, the host defense activity of alveolar macrophages was impaired by in vivo exposure to 0.2 ppm ozone. In particular, the C. albicans-associated defect lasted throughout the exposure period.

Toll-like receptors: molecular mechanisms of the mammalian immune response.

The unrelenting bombardment by microbial pathogens from the environment and their increasing resistance to medical treatments are a constant threat to the survival of all organisms on earth. Microbes are covered by molecular patterns that are common among a broad range of pathogens. These include the lipopolysaccharides (LPS) of Gram-negative bacteria, lipoteichoic acids of Gram-positive bacteria, lipoproteins of bacteria and parasites, glycolipids of mycobacteria, mannans of yeast and double-stranded RNAs of viruses.1,2 Recognition of and responses to these molecules are controlled by a wide variety of cellular receptors. The best characterized receptors are the T-cell receptor and B-cell antibody receptor of the adaptive immune response, the specificity of which is randomly generated and clonally selected during the development of T and B lymphocytes.3 Unlike the receptors of the adaptive immune system, the pattern recognition receptors of the innate immune system have predetermined specificity generated early on in evolution and play an essential role in the determination of self versus non-self during the initial rapid responses to infection.1,2 As described in this review, a family of cell surface receptors, termed Toll-like receptors, are emerging as key regulators of host responses to infection.

Release of monocyte chemoattractant protein (MCP)-1 by a human alveolar epithelial cell line in response to Mycobacterium avium

Clinical strains of Mycobacterium avium isolated from patients with acquired immunodeficiency syndrome, but not a non-clinical laboratory strain (ATCC 25291), were found to stimulate the human alveolar epithelial cell line A549, to produce monocyte chemoattractant protein (MCP)-1. A549 cells were also found to produce elevated levels of MCP-1 in response to sonicates of the clinical strains of M. avium, and surprisingly, the non-clinical strain as well. However, sonic extracts of the clinical strains were found to induce significantly higher levels of MCP-1 production compared to extracts of the non-clinical strain ( P<0.001). These data suggest the existence of strain-related differences in antigen expression by M. avium. The clinical and non-clinical strains of M. avium were found to attach and invade, but not replicate in A549 cells indicating that MCP-1 production by A549 cells does require the presence of viable, replicating organisms. Activation of alveolar epithelial cells by exposure to M. avium resulting in the production of chemokines which recruit inflammatory cells to the site of infection may be an important regulatory pathway for the activation of pulmonary host defense.

Release of monocyte chemoattractant protein (MCP)-1 by a human alveolar epithelial cell line in response to mycobacterium avium.

Clinical strains of Mycobacterium avium isolated from patients with acquired immunodeficiency syndrome, but not a non-clinical laboratory strain (ATCC 25291), were found to stimulate the human alveolar epithelial cell line A549, to produce monocyte chemoattractant protein (MCP)-1. A549 cells were also found to produce elevated levels of MCP-1 in response to sonicates of the clinical strains of M. avium, and surprisingly, the non-clinical strain as well. However, sonic extracts of the clinical strains were found to induce significantly higher levels of MCP-1 production compared to extracts of the non-clinical strain (P < 0.001). These data suggest the existence of strain-related differences in antigen expression by M. avium. The clinical and non-clinical strains of M. avium were found to attach and invade, but not replicate in A549 cells indicating that MCP-1 production by A549 cells does require the presence of viable, replicating organisms. Activation of alveolar epithelial cells by exposure to M. avium resulting in the production of chemokines which recruit inflammatory cells to the site of infection may be an important regulatory pathway for the activation of pulmonary host defense.

The interleukin-1 receptor/Toll-like receptor superfamily: signal transduction during inflammation and host defense.

The signal transduction pathways activated by the proinflammatory cytokine interleukin-1 (IL-1) have been the focus of much attention because of the important role that IL-1 plays in inflammatory diseases. A number of proteins have been described that participate in the post-receptor activation of the transcription factor nuclear factor kappaB (NF-kappaB), and stress-activated protein kinases such as p38 mitogen-activated protein kinase (MAPK). It has also emerged that the type I IL-1 receptor (IL-1RI) is a member of an expanding receptor superfamily. These related receptors all have sequence similarity in their cytosolic regions. The family includes the Drosophila melanogaster protein Toll, the IL-18 receptor (IL-18R), and 10 Toll-like receptors (TLRs), TLR-1 to TLR-10, which bind to microbial products, activating host defense responses. Because of the similarity of IL-1RI to Toll, the conserved sequence in the cytosolic region of these proteins has been termed the Toll-IL-1 receptor (TIR) domain. The same proteins activated during signaling by IL-1RI also participate in signaling by other receptors with TIR domains. The receptor superfamily is evolutionarily conserved; members also occur in plants and insects, where they also function in host defense. The signaling proteins that are activated are also conserved across species. Differences are, however, starting to emerge in signaling pathways activated by different receptors. This receptor superfamily, therefore, represents an ancient signaling system that is a critical determinant of the innate immune and inflammatory responses.

Diurnal Variations in Lipopolysaccharide-Induced Sleep, Sickness Behavior and Changes in Corticosterone Levels in the Rat

Inoculation of rats with microorganisms or microbial constituents that activate host defense promotes non-rapid eye movement sleep (non-REMS) and suppresses REMS. In this study, we evaluated circadian influences on the effects of lipopolysaccharide (LPS) on sleep, sickness behavior and plasma corticosterone levels in the rat. Three sets of experiments were performed. In each, the animals were intraperitoneally injected with vehicle for LPS (30 µg/kg) during 2 consecutive days, at the beginning of either the circadian rest or the activity phase. In experiment 1, sleep-wake behavior and brain temperature were recorded, and in experiment 2, core body temperature, locomotor activity as well as food and water intake. In experiment 3, corticosterone blood levels were measured. The results show that LPS-evoked changes in temperature, sleep and other behavioral parameters depend markedly on the time of day LPS is administered. However, a direct comparison of the LPS data demonstrates that, except for sleep parameters, the absolute time course of the assessed parameters was rather similar between the rest and activity phases. These findings suggest that LPS evokes a state characterized by high temperature and low vigilance, which is reached independently of the circadian phase.

Dose-dependent effects of endotoxin on human sleep

The role of the central nervous system in the host response to infection and inflammation and modulation of these responses by the hypothalamic-pituitary-adrenal system are well established. In animals, activation of host defense mechanisms increases non-rapid eye movement (NREM) sleep amount and intensity, which, in turn, are thought to support host defense, or the body's ability to defend itself against challenges to its immune system. In humans, the evidence is conflicting. Therefore, we investigated the effects of three placebo-controlled doses of endotoxin on host response, including nocturnal sleep in healthy volunteers. Administered before nocturnal sleep onset, endotoxin dose dependently increased rectal temperature, heart rate, and the plasma levels of tumor necrosis factor (TNF)-alpha, soluble TNF receptors, interleukin (IL)-1 receptor antagonist, IL-6, and cortisol. The lowest dose reliably increased circulating levels of cytokines and soluble cytokine receptors, but it did not affect rectal temperature, heart rate, or cortisol. This subtle host defense activation increased deep NREM sleep amount, often referred to as slow-wave sleep (stages 3 and 4), and intensity (delta power). Conversely, the highest dose of endotoxin disrupted sleep. Whereas it is well established that the endocrine and thermoregulatory systems are very sensitive to endotoxin, this study shows that human sleep-wake behavior is even more sensitive to activation of host defense mechanisms.

Interleukin-1 and Cutaneous Inflammation: A Crucial Link Between Innate and Acquired Immunity

As our primary interface with the environment, the skin is constantly subjected to injury and invasion by pathogens. The fundamental force driving the evolution of the immune system has been the need to protect the host against overwhelming infection. The ability of T and B cells to recombine antigen receptor genes during development provides an efficient, flexible, and powerful immune system with nearly unlimited specificity for antigen. The capacity to expand subsets of antigen-specific lymphocytes that become activated by environmental antigens (memory response) is termed "acquired" immunity. Immunologic memory, although a fundamental aspect of mammalian biology, is a relatively recent evolutionary event that permits organisms to live for years to decades. "Innate" immunity, mediated by genes that remain in germ line conformation and encode for proteins that recognize conserved structural patterns on microorganisms, is a much more ancient system of host defense. Defensins and other antimicrobial peptides, complement and opsonins, and endocytic receptors are all considered components of the innate immune system. None of these, however, are signal-transducing receptors. Most recently, a large family of cell surface receptors that mediate signaling through the NF-kappaB transcription factor has been identified. This family of proteins shares striking homology with plant and Drosophila genes that mediate innate immunity. In mammals, this family includes the type I interleukin-1 receptor, the interleukin-18 receptor, and a growing family of Toll-like receptors, two of which were recently identified as signal-transducing receptors for bacterial endotoxin. In this review, we discuss how interleukin-1 links the innate and acquired immune systems to provide synergistic host defense activities in skin.

White blood cells and cortisol after sleep deprivation and recovery sleep in humans.

Sleep deprivation (SD) has enriched our treatment programme for major depression. SD has been demonstrated to modify different host defence activities. There is some evidence that there are reciprocal relationships between immune function and increased hypothalamic-pituitary-adrenocortical (HPA) axis activity in depression. We therefore investigated the number of leukocytes, granulocytes, monocytes, lymphocytes, B cells, T cells, helper T cells, cytotoxic T cells, NK cells and salivary cortisol in 10 healthy men before and after total SD (TSD) as well as after recovery sleep. Blood samples were drawn on 3 consecutive days at 7 am, 1 pm and 7 pm, respectively. Comparison of the 7 am values by contrast analysis yielded significant differences for granulocytes (p = 0.044) and NK cells (p = 0.001) after SD and recovery sleep. NK cells decreased and granulocytes increased after SD and after recovery sleep. Significant differences between single points in time across the day were found for granulocytes (p = 0.022), monocytes (p = 0.031), T cells (p = 0.005), helper T cells (p = 0.004), cytotoxic T cells (p = 0.005) and NK cells (p = 0.017). No significant difference could be detected for leukocytes, lymphocytes and B cells counts. These results favour the thesis that SD and recovery sleep lead to changes in the distribution of peripheral leukocytes, especially in a reduction of NK cells after SD and recovery sleep. The cortisol rhythm was affected neither by SD nor recovery sleep.

Experimental immunomodulation, sleep, and sleepiness in humans.

Infection, inflammation, and autoimmune processes are accompanied by serious disturbances of well-being, psychosocial functioning, cognitive performance, and behavior. Here we review those studies that have investigated the effects of experimental immunomodulation on sleep and sleepiness in humans. In most of these studies bacterial endotoxin was injected intravenously to model numerous aspects of infection including the release of inflammatory cytokines. These studies show that human sleep-wake behavior is very sensitive to host defense activation. Small amounts of endotoxin, which affect neither body temperature nor neuroendocrine systems but slightly stimulate the secretion of inflammatory cytokines, promote non-rapid-eye-movement sleep amount and intensity. Febrile host responses, in contrast, go along with prominent sleep disturbances. According to present knowledge tumor necrosis factor-alpha (TNF-alpha) is most probably a key mediator of these effects, although it is likely that disturbed sleep during febrile host responses involves endocrine systems as well. There is preliminary evidence from human studies suggesting that inflammatory cytokines such as TNF-alpha not only mediate altered sleep-wake behavior during infections, but in addition are involved in physiological sleep regulation and in hypnotic effects of established sedating drugs.

Protective specific immunity induced by doxorubicin plus TNF-alpha combination treatment of EL4 lymphoma-bearing C57BL/6 mice.

The therapeutic efficacy of a single (day 8), moderate dose (4 mg/kg, i.v.) of doxorubicin (DOX, Adriamycin) combined with recombinant human TNF-alpha (3 different doses and 5 different schedules, i.v.) was evaluated in C57BL/6 mice bearing an implant (s.c.) of the DOX-sensitive, TNF-alpha-resistant EL4 lymphoma. In parallel to monitoring survival, the levels of several host anti-tumor cytolytic effector functions of splenocytes and thymocytes were evaluated throughout the treatment period and in long-term survivors (LTS). DOX treatment alone resulted in a moderate (approx. 20%) increase in life span but no cures. TNF-alpha alone, at any tested dose or schedule, had little or no positive effect on survival. The combinations of DOX and TNF-alpha were only slightly better than DOX alone with respect to the time to death of mice that died (approx. 29% increase); however, each of the combinations involving 1,000 U TNF-alpha/injection produced a fraction (20% to 80%) of LTS. The host defense activities examined included those of splenic and thymic cytolytic T lymphocytes (CTL) and lymphokine-activated killer cells as well as splenic tumoricidal macrophages. Although most activities were modulated by tumor growth and/or treatment, only CTL responsiveness appeared to correlate with survival. CTL activity in the treated groups with LTS was significantly higher than in control groups late in the treatment period. Finally, ex vivo analyses of splenocytes and thymocytes together with the rejection of implanted tumor at 17 months established that LTS displayed specific long-term immune memory.

Role of complement in in vitro and in vivo lung inflammatory reactions.

Complement is one of the integral buttresses of the inflammatory response. In addition to host defense activities, proinflammatory properties of several complement components are described. This overview elucidates the role of complement in inflammatory reactions in vitro and in vivo, focusing on the complement activation products, C5a, and the membrane attack complex, C5b-9. Using several approaches, the impact of these complement components in mechanisms relevant to neutrophil recruitment is emphasized. In addition, the participation of complement in endothelial superoxide generation and its essential requirement for full expression of lung injury is demonstrated, as are the involved intracellular signal transduction pathways. Understanding the mechanisms of complement-induced proinflammatory effects may provide a basis for future therapeutic blockade of complement and/or its activation products.

Cafeteria feeding induces interleukin-1beta mRNA expression in rat liver and brain.

intake affects gut-immune function and can provide a strong intestinal antigen challenge resulting in activation of host defense mechanisms in the digestive system. Previously, we showed that feeding rats a cafeteria diet increases non-rapid eye movement sleep by a subdiaphragmatic mechanism. Food intake and sleep regulation and the immune system share the regulatory molecule interleukin-1beta (IL-1beta). Thus this study examined the effects of a cafeteria diet on IL-1beta mRNA and IL-1 receptor accessory protein (IL-1RAP) mRNA expression in rat liver and brain. Rats were fed normal rat chow or a palatable diet consisting of bread, chocolate, and shortbread cookies (cafeteria diet). After 3 days, midway between the light period of the light-dark cycle, rats were killed by decapitation. Feeding rats a cafeteria diet resulted in increased IL-1beta mRNA expression in the liver and hypothalamus compared with rats fed only the normal rat chow. In addition, cafeteria feeding decreased IL-1RAP mRNA levels in the liver and brain stem. These results indicate that feeding has direct effects on cytokine production and together with other data suggest that the increased sleep that accompanies increased feeding may be the result of increased brain IL-1beta. These results further suggest that cytokine-to-brain communication may be important in normal physiological conditions, such as feeding, as well as being important during inflammatory responses.

Cytokine-mediated Down-regulation of CYP1A1 in Hepa1 Cells

The activation of host defense mechanisms down-regulates microsomal cytochrome P450 in cell culture, humans, and animals. Investigation into various aspects of this effect using in vivo models has yet to define clearly the role that cytokines play in this phenomenon. The mechanism of down-regulation by immunostimulants, such as lipopolysaccharide (LPS), is explored with an in vitro model, utilizing a murine hepatoma (Hepa1) and a murine macrophage (IC-21) cell line. It is hypothesized that down-regulation of P450 activity by immunostimulants involves the activation of immune cells and the subsequent release of cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The effects of immunostimulation on P450 activity are assessed by ethoxyresorufin O-dealkylase, an assay that measures CYP1A activity in Hepa1 cells. Initial studies demonstrated that LPS added directly to hepatoma cells had no effect on the levels of CYP1A1 activity. In contrast, a significant down-regulation in CYP1A1 activity occurred when hepatoma cells were incubated with monocyte conditioned medium obtained by incubating LPS with IC-21 cells. When pentoxifylline, a TNF-α synthesis inhibitor, was co-administered with LPS to macrophages, the down-regulation of CYP1A1 activity was prevented. The direct administration of murine recombinant TNF-α to hepatoma cells resulted in a down-regulation of CYP1A1 activity. These results implicated the release of TNF-α from macrophages as an important step in the down-regulation of CYP1A1 by LPS.

72-kDa and 92-kDa gelatinases in saliva of patients with human inmmunodeficiency virus infection

Human immunodeficiency virus (HIV) infection has been associated with periodontal diseases in HIV-seropositive patients. In periodontal diseases, matrix metalloproteinases (MMPs) may play key roles in the extracellular matrix, basement membrane, serpin degradation, and modification of cytokine action. We characterized the 72 kDa type IV collagenase (gelatinase A, MMP-2) and 92 kDa type IV collagenase (gelatinase B, MMP-9) in the saliva of HIV-seropositive patients and seronegative healthy controls by activity measurements and quantitative immunoblotting. Immunoblot analysis with specific antibodies against MMP-2 and MMP-9 and their tissue inhibitors (TIMP-1, TIMP-2) disclosed that, independent of the phase of the patients' HIV infection, their salivary samples contained higher amounts of MMP-2 and MMP-9 immunoreactivities in pro- and active forms and the TIMP-1 and TIMP-2 inhibitors than did the control samples. Healthy control saliva contained only slight immunoreactivities for gelatinases and TIMPs. However, as judged by the studied clinical and microbiologic indicators, HIV-seropositive patients showed only a slight tendency to develop periodontitis. Overall, an increased amount of gelatinases in saliva may reflect increased host response and defense activities in HIV infection.

Involvement of T cells in enhanced resistance to Klebsiella pneumoniae septicemia in mice treated with liposome-encapsulated muramyl tripeptide phosphatidylethanolamine or gamma interferon.

We have previously shown that prophylactic administration of the liposome-encapsulated immunomodulating agents muramyl tripeptide phosphatidylethanolamine (MTPPE) and gamma interferon (IFN-gamma) results in strongly increased survival of mice from a normally lethal septicemia with Klebsiella pneumoniae. It was anticipated that the treatment acts on macrophages and nonspecifically augments host resistance to various infections. In the present study, we provide evidence for a key role for T cells in host defense potentiation by the liposomal immunomodulators toward K. pneumoniae septicemia. It is shown that both CD4 and CD8 cells are important in immunomodulation, most likely due to production of IFN-gamma. Depletion of circulating IFN-gamma resulted in strong reduction of the antimicrobial host defense activation. Administration of interleukin-10 resulted in decreased antimicrobial host defense activation by liposomal immunomodulators. Moreover, administration of liposomal immunomodulators was shown to induce predominantly T-helper type 1 (Th1) cell populations in the spleen. These findings indicate that immunomodulation with liposomal MTPPE and IFN-gamma favors Th1 and NK cell activation.

Activation of Host Defense Mechanisms by Elevated Production of H2O2 in Transgenic Plants.

Active oxygen species have been postulated to perform multiple functions in plant defense, but their exact role in plant resistance to diseases is not fully understood. We have recently demonstrated H2O2-mediated disease resistance in transgenic potato (Solanum tuberosum) plants expressing a foreign gene encoding glucose oxidase. In this study we provide further evidence that the H2O2-mediated disease resistance in potato is effective against a broad range of plant pathogens. We have investigated mechanisms underlying the H2O2-mediated disease resistance in transgenic potato plants. The constitutively elevated levels of H2O2 induced the accumulation of total salicylic acid severalfold in the leaf tissue of transgenic plants, although no significant change was detected in the level of free salicylic acid. The mRNAs of two defense-related genes encoding the anionic peroxidase and acidic chitinase were also induced. In addition, an increased accumulation of several isoforms of extracellular peroxidase, including a newly induced one, was observed. This was accompanied by a significant increase in the lignin content of stem and root tissues of the transgenic plants. The results suggest that constitutively elevated sublethal levels of H2O2 are sufficient to activate an array of host defense mechanisms, and these defense mechanisms may be a major contributing factor to the H2O2-mediated disease resistance in transgenic plants.

Tumor vascular endothelium: barrier or target in tumor directed drug delivery and immunotherapy.

The therapy of solid tumors with conventional chemotherapeutics, drug delivery preparations and immunomodulatory agents directed against the tumor cells is corrupted by a major barrier presented by the tumor vasculature. Permeability of the tumor blood vessels for transport of small molecules and macromolecular drug-carrier conjugates is only sufficient in the blood vessels at the tumor-host interface. Downregulation of the expression of adhesion molecules, required for the facilitation of immune cell recruitment, by the tumor vascular endothelium results in an escape of the tumor from host defence. New therapeutic approaches for the treatment of solid tumors are aimed at the tumor vasculature, either at the endothelial cells themselves or at basement membrane or tumor stroma components. Angiogenesis can be directly blocked with angiogenesis inhibitors, while angiogenesis related factors can serve as tumor vasculature specific epitopes for drug delivery strategies. Some glycoproteins expressed by tumor endothelial cells or present in the basement membrane and tumor stroma are also potential tumor selective targets. Therapeutic modalities that are suitable for site specific delivery are agents that increase tumor accumulation of (targeted) chemo/radiotherapeutics through increasing tumor vascular permeability. The observation that for tumor growth the blood supply is a limiting factor, led to the development of strategies to inhibit angiogenesis or block the tumor blood flow. Manipulation of the expression of endothelial cell adhesion molecules by selectively delivering modulatory agents at or in the tumor vascular endothelial cells may induce (bispecific antibody mediated) host defense activity directed against the tumor cells.

Interleukin-1 alpha, interleukin-8 and interferon-alpha levels in gingival crevicular fluid.

Cytokines play an important role in the pathology associated with chronic inflammatory diseases. We measured the total amounts [picograms (pg)] and concentrations.(pg/microliter) of interleukin-1 alpha (IL-1 alpha), interleukin-8 (IL-8) and interferon-alpha (IFN-alpha) in 20 s gingival crevicular fluid (GCF) samples obtained from 2 diseased and 2 healthy sites in 20 subjects with periodontitis, and from 2 healthy sites in 20 subjects without disease. Both the mean amount and concentration of IL-1 alpha were significantly higher (p < 0.001) in diseased sites compared to healthy sites in subjects with disease. The results for IL-8 and IFN-alpha differed depending on the method of reporting. Whereas the amount of IL-8 was significantly higher (p < 0.01) in diseased sites, the mean concentration of IL-8 was lower compared to healthy sites. The mean amount of IFN-alpha was similar in health and disease; however, the concentration of IFN-alpha was significantly lower in diseased sites (p < 0.001) corresponding to the significant increase in crevicular fluid volume (p < 0.001). There were no significant differences in the amount or concentrations of the 3 cytokines between healthy sites from subjects with disease and healthy sites from healthy controls. The total amounts of both IFN-alpha and IL-8 were correlated between healthy and diseased sites in subjects. These data suggest that, while the disease status of a site is the major determinant of the levels of these cytokines locally, subjects with high levels of IL-8 and IFN-alpha in healthy sites also tend to have high levels of these cytokines in diseased sites. Finally, both the concentrations and total amounts of IL-8 and IFN-alpha were significantly correlated in diseased sites, suggesting that levels of these two cytokines rise or fall in tandem. The combination of decreased IL-8 and decreased IFN-alpha concentrations at diseased sites may reflect the reduced anti-bacterial host defense activity at that site.