Complement research: biosynthesis, genetics, immunoregulatory role and clinical studies

Histamine Promotes the Release of Interleukin-6 via the H1R/p38 and NF-κB Pathways in Nasal Fibroblasts

Purpose

Based on the close relationship between histamine and interleukin 6 (IL-6), we hypothesized that histamine may regulate the production of cytokines, such as IL-6, during allergic inflammation. Here, we examined the role of histamine in IL-6 production and histamine receptor activity in nasal fibroblasts, along with the mechanisms underlying these effects.

Methods

Experiments were performed using nasal fibroblasts from 8 normal patients. RT-PCR was used to identify the major histamine receptors expressed in nasal fibroblasts. Fibroblasts were then treated with histamine with or without histamine-receptor antagonists, and monitored for IL-6 production using an ELISA. Four potential downstream signaling molecules, p38, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and NF-κB, were evaluated by Western blot, and a luciferase reporter assay.

Results

Elevated expression was seen for all histamine receptors, with IL-6 protein levels increasing significantly following histamine stimulation. Among the histamine-receptor specific antagonists, only the H1R antagonist significantly decreased IL-6 production in histamine-stimulated nasal fibroblasts. Histamine increased the expression level of phosphorylated p38 (pp38), pERK, and pJNK, as well as NF-κB induction. The H1R antagonist actively suppressed pp38 and NF-κB expression in histamine-induced nasal fibroblasts, but not pERK and pJNK. The p38 inhibitor strongly attenuated IL-6 production in histamine-stimulated nasal fibroblasts.

Conclusions

The data presented here suggest that antihistamines may be involved in the regulation of cytokines, such as IL-6, due to the role of histamine as an inflammatory mediator in nasal fibroblasts.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

The effect of ranitidine on antibody responses to polysaccharide vaccines in patients with B-cell chronic lymphocytic leukaemia

OBJECTIVES

To analyse the effects of ranitidine treatment on vaccination induced antibody responses in patients with chronic lymphocytic leukaemia (CLL).

METHODS

Fifty CLL patients were vaccinated with tetanus conjugated Hib vaccine and a 23-valent pneumococcal polysaccharide vaccine with (n = 25) or without (n = 25) ranitidine treatment in a matched case--control setting. Anti tetanus toxoid (TT), anti-Hib and anti-pneumococcal antibody levels were determined before and after vaccination. Additionally, cytokine levels were assessed in patients treated with ranitidine.

RESULTS

Vaccination-induced increases in anti-Hib and anti-TT antibody levels were higher in the ranitidine group compared with the control group. Anti-pneumococcal antibody responses were not improved by administration of ranitidine. Higher levels of IL-18 were found in patients treated with ranitidine compared with healthy controls. Levels of IL-6, IL-8, IL-18, RANTES, IP-10, sVCAM-1 and sICAM-1 were within normal ranges and did not change during ranitidine treatment.

CONCLUSION

Ranitidine treatment improves vaccination-induced T-cell dependent antibody responses in patients with CLL but has no beneficial effect on the response to vaccination with unconjugated polysaccharide antigens.

Current concepts in neuroendocrine cancer metabolism

Neuroendocrine (NE) cancers occur in multiple anatomic locations and range in prognosis from indolent to aggressive. In addition, adenocarcinomas can express gene products associated with NE cells, referred to as NE differentiation (NED), which correlates with poor prognosis and aggressive disease. Several metabolites and peptides produced by NE cells have been discovered that engage in cellular signaling and have autocrine and paracrine effects on cancer cell proliferation. This review focuses on the current knowledge of small molecule metabolism in NE cancers involving the synthesis of biogenic amine, polyamine, and amino acid neurotransmitters. Systems biology-directed approaches to NE cancer metabolism using gene expression profiling, liquid chromatography/mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR) are also discussed. Furthermore, knowledge of metabolic and signaling pathways in NE cancers has led to the successful implementation of therapeutic regimens in cell culture and animal models of NE carcinogenesis.

Histamine release during adult cardiopulmonary bypass

Histamine, an inflammatory mediator in its own right, may also be a marker for a more widespread systemic inflammatory process. In this study we have examined variations in plasma histamine concentrations produced during the course of cardiac surgery involving cardiopulmonary bypass, the relationship between these variations and intra-operative events. By assays of serum tryptase and CD-63 expression we have also attempted to identify the source of histamine. Histamine concentrations that were significantly raised from baseline level were demonstrated. These were elevated from the time of aortic cross-clamping and continued to be raised for 24 h postoperatively (p < 0.00625). This was associated with an increase in CD-63 expression (p < 0.025) (but not an increase in tryptase concentration) following aortic cross-clamping and protamine administration, suggesting that basophils are the source of histamine. 41% of patients had arrhythmias in the post bypass period. The rise in histamine levels was not related to the incidence of cardiac arrhythmias.

Cytokine dysregulation, inflammation and well-being

Cytokines mediate and control immune and inflammatory responses. Complex interactions exist between cytokines, inflammation and the adaptive responses in maintaining homeostasis, health, and well-being. Like the stress response, the inflammatory reaction is crucial for survival and is meant to be tailored to the stimulus and time. A full-fledged systemic inflammatory reaction results in stimulation of four major programs: the acute-phase reaction, the sickness syndrome, the pain program, and the stress response, mediated by the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Common human diseases such as atopy/allergy, autoimmunity, chronic infections and sepsis are characterized by a dysregulation of the pro- versus anti-inflammatory and T helper (Th)1 versus Th2 cytokine balance. Recent evidence also indicates the involvement of pro-inflammatory cytokines in the pathogenesis of atherosclerosis and major depression, and conditions such as visceral-type obesity, metabolic syndrome and sleep disturbances. During inflammation, the activation of the stress system, through induction of a Th2 shift, protects the organism from systemic 'overshooting' with Th1/pro-inflammatory cytokines. Under certain conditions, however, stress hormones may actually facilitate inflammation through induction of interleukin (IL)-1, IL-6, IL-8, IL-18, tumor necrosis factor-alpha and C-reactive protein production and through activation of the corticotropin-releasing hormone/substance P-histamine axis. Thus, a dysfunctional neuroendocrine-immune interface associated with abnormalities of the 'systemic anti-inflammatory feedback' and/or 'hyperactivity' of the local pro-inflammatory factors may play a role in the pathogenesis of atopic/allergic and autoimmune diseases, obesity, depression, and atherosclerosis. These abnormalities and the failure of the adaptive systems to resolve inflammation affect the well-being of the individual, including behavioral parameters, quality of life and sleep, as well as indices of metabolic and cardiovascular health. These hypotheses require further investigation, but the answers should provide critical insights into mechanisms underlying a variety of common human immune-related diseases.

Acute inflammatory reactions caused by histamine via monocytes/macrophages chronically participate in the initiation and progression of atherosclerosis

Previously we demonstrated that histidine decarboxylase (HDC), which produces histamine from l-histidine, was detected in monocytes/macrophages located in human atherosclerotic lesions. As monocytic migration is a key event of atherogenesis, we investigated whether histamine induces monocytic expression of monocyte chemoattractant protein (MCP)-1 and its receptors CCR2-A and -B, and also endothelial expression of ICAM-1 and VCAM-1. Furthermore, we studied the effect of interleukin (IL)-4, which inhibits the HDC expression, on the expression of MCP-1 and CCR2. Histamine stimulated monocytes, but not macrophages, to express MCP-1 and CCR2-A and -B. The expression of MCP-1 was inhibited by histamine H2 blocker. In contrast, IL-4 enhanced CCR2 expression but not MCP-1. Histamine stimulated endothelial cells to express ICAM-1 and VCAM-1. These results indicate that histamine and IL-4, which are both synthesized in the arterial intima, chronically participates in the pathogenesis of atherosclerosis via the enhanced expression of monocytic MCP-1, CCR2 and endothelial adhesion molecules.

Histidine decarboxylase expression in pancreatic endocrine cells and related tumors

Histidine decarboxylase (HDC) is an enzyme for decarboxylating l-histidine to histamine and is expressed in various types of cells including neuroendocrine tumors. Recent findings have demonstrated a high percentage of HDC immunoreactivity in many neuroendocrine tumors, including carcinoid tumors, small cell carcinomas of the lung, pheochromocytomas, and medullary carcinomas of the thyroid. HDC immunostaining was applied to pancreatic islet cells and related tumors to explore possible expression of HDC as a wide spectrum marker for neuroendocrine differentiation. A total of 24 cases (22 pancreatic endocrine neoplasms, one small cell carcinoma of the pancreas, and one mixed exocrine-endocrine carcinoma) along with normal pancreatic tissue were immunostained with the anti-HDC antibody. In a normal pancreas, a double immunostaining revealed possible colocalization of HDC with glucagon- or insulin-positive cells in the islets. Seventeen of 22 pancreatic endocrine neoplasms (77%) were found to be positive for HDC, and no distinct relation to hormonal activity was observed. One small cell carcinoma was strongly positive to HDC. One non-functional tumor with mixed exocrine and endocrine components showed a diffuse positive immunostaining for HDC, and some neoplastic glucagon- or somatostatin (SRIF)-positive cells coexpressed HDC. In conclusion, we demonstrated that the majority of pancreatic endocrine tumors expressed HDC, and we suggest that HDC is a wider new marker for neuroendocrine differentiation.

Effect of histamine on the production of matrix metalloproteinases-1, -3, -8 and -13, and TNF? and PGE2 by human articular chondrocytes and synovial fibroblasts in vitro: a comparative study

Histamine has many regulatory activities and is well recognised for its importance in allergic and inflammatory disorders. Recently, histamine has been implicated in the pathophysiological processes of both rheumatoid and osteoarthritis, where human articular chondrocytes (HACs) and rheumatoid synovial fibroblasts (RSFs) are reported to express histamine receptors. This study has demonstrated H(1) and H(2) histamine receptors using immunohistochemistry on HACs and RSFs in vitro and has compared the effects of histamine (20 microM) on both cell types with regard to the production of matrix metalloproteinases (MMPs-1, -3, -8 and -13), the proinflammatory cytokine tumour necrosis factor alpha (TNFalpha) and prostaglandin E(2) (PGE(2)). On incubation with histamine, HACs showed increased production of MMP-3, MMP-13, TNFalpha and PGE(2) (statistical significance P=0.02, 0.005, 0.008 and 0.03, respectively, student's t-test), but MMP-1 expression was unaffected. In contrast, the RSF showed a histamine-induced increase in MMP-1 ( P=0.028) and an approximate 10-fold level of MMP-3 and PGE(2) release over that of HACs, each being stimulated by histamine ( P=0.02 and 0.032, respectively, student's t-test). However, MMP-8, MMP-13 and TNFalpha were not detected for RSF cultures. Our results show that histamine modifies the behaviour of both HACs and RSFs in vitro, but different effects were observed for the production of specific MMPs and TNFalpha by the two cell types.

Microarray analysis supports a role for ccaat/enhancer-binding protein-beta in brain injury

CCAAT/enhancer-binding protein-beta (C/EBPbeta) is a transcription factor that plays an important role in regulating cell growth and differentiation. This protein plays a central role in lymphocyte and adipocyte differentiation and hepatic regeneration and in the control of inflammation and immunity in the liver and in cells of the myelomonocytic lineage. Our previous studies suggested that this protein could also have important functions in the brain. Therefore, we were interested in the identification of downstream targets of this transcription factor in cells of neural origin. We performed cDNA microarray analysis and found that a total of 48 genes were up-regulated in C/EBPbeta-overexpressing neuronal cells. Of the genes that displayed significant changes in expression, several were involved in inflammatory processes and brain injury. Northern blot analysis confirmed the up-regulation of ornithine decarboxylase, 24p3/LCN2, GRO1/KC, spermidine/spermine N(1)-acetyltransferase, xanthine dehydrogenase, histidine decarboxylase, decorin, and TM4SF1/L6. Using promoter-luciferase reporter transfection assays, we showed the ornithine decarboxylase and 24p3 genes to be biological downstream targets of C/EBPbeta in neuroblastoma cells. Moreover, the levels of C/EBPbeta protein were significantly induced after neuronal injury, which was accompanied by increased levels of cyclooxygenase-2 enzyme. This strongly supports the concept that C/EBPbeta may play an important role in brain injury.

Dry environment increases mast cell number and histamine content in dermis in hairless mice

BACKGROUND

A variety of skin diseases, such as atopic dermatitis, senile xerosis or psoriasis tends to worsen during the dry winter season. These skin diseases are also characterized by itch sensation.

OBJECTIVES

To evaluate the generation of histamine in the dermis of hairless mice kept under various conditions of environmental humidity.

MATERIALS AND METHODS

We carried out the quantification of mast cell population and evaluated the histamine content in the epidermis, dermis and serum of the mice kept under various conditions of environmental humidity.

RESULTS

Histamine content in the dermis of the mice kept in a low environmental humidity (relative humidity < 10%) for 3 and 5 days was significantly higher than that of the mice kept in a high environmental humidity (relative humidity > 80%) for the same period of time. No significant difference was observed on the histamine content in the epidermis between the two humidity groups. The number of mast cells in the dermis of the mice kept in the low environmental humidity was significantly higher than that of the mice kept in the high environmental humidity. Topical application of petrolatum reduced the level of histamine in the dermis of the mice under the low environmental humidity.

CONCLUSIONS

These results suggest that a low environmental humidity increases mast cell number and dermal histamine content.

Regulation by prostaglandin E2 and histamine of angiogenesis in inflammatory granulation tissue

In an air pouch-type carrageenin-induced inflammation model in rats, the selective cyclooxygenase (COX)-2 inhibitor NS-398 dose dependently inhibited the granulation tissue formation, angiogenesis and the level of vascular endothelial growth factor (VEGF) in the granulation tissue. In culture of the minced granulation tissue, PGE2 induced VEGF production in a concentration-dependent manner. Histamine also induced VEGF production in the granulation tissue in vitro. The H2 receptor antagonist cimetidine, the cAMP antagonist Rp-cAMP and the protein kinase A inhibitor H-89 suppressed the histamine-induced VEGF production in the granulation tissue. However, the H1 receptor antagonist pyrilamine maleate, the H3 receptor antagonist thioperamide, the protein kinase C inhibitors Ro 31-8425 and calphostin C or the tyrosine kinase inhibitor genistein showed no effect. Subcutaneous implantation of a cotton thread in the dorsum of histidine decarboxylase-deficient (HDC-/-) mice, but not in mast cell-deficient (WBB6F1-W/Wv) mice, induced less angiogenesis with lower levels of VEGF in the granulation tissue than in their corresponding wild-type (HDC+/+ and WBB6F1(-)+/+) mice. In HDC-/- mice, the topical injection of histamine or the H2 receptor agonist dimaprit rescued the defective angiogenesis and granulation tissue formation. In addition, cimetidine but not pyrilamine maleate and thioperamide inhibited the histamine-induced angiogenesis in the granulation tissue in HDC-/- mice. These findings suggest that PGE2 and histamine augment angiogenesis in the inflammatory granulation tissue by inducing VEGF production, and histamine induces VEGF production possibly through the H2 receptor--cAMP--protein kinase A pathway.

Augmented lipopolysaccharide-induction of the histamine-forming enzyme in streptozotocin-induced diabetic mice

Disorders of the microcirculation and reduced resistance to infection are major complications in diabetes. Histamine enhances capillary permeability, and may also reduce cellular immunity. Here we demonstrate that streptozotocin (STZ)-induced diabetes in mice not only enhances the activity of the histamine-forming enzyme, histidine decarboxylase (HDC), but also augments the lipopolysaccharide (LPS)-induced elevation of HDC activity in various tissues, resulting in a production of histamine. The augmentation of HDC activity occurred as early as 2 days after STZ injection, but was not seen in nondiabetic mice. When given to STZ-treated mice, nicotinamide, an inhibitor of poly(ADP-ribose) synthetase, reduced both the elevation of blood glucose and the elevations of HDC activity and histamine production. These results suggest that hyperglycemia may initiate a sequence of events leading not only to an enhancement of basal HDC activity, but also to a sensitization of mice to the HDC-inducing action of LPS. We hypothesize that bacterial infections and diabetic complications may mutually exacerbate one another because both involved an induction of HDC.

Urinary excretion of N-methylhistamine as a marker of disease activity in inflammatory bowel disease

OBJECTIVE

Mast cells are thought to participate in the pathogenesis of inflammatory bowel disease (IBD). In this study, urinary excretion of N-methylhistamine (UMH), a stable metabolite of the mast cell mediator histamine, was evaluated as an indicator of disease activity in patients with IBD.

METHODS

Urinary excretion of UMH (microg/mmol creatinine x m2 body surface area) was measured by radioimmunoassay in 55 controls, 56 patients with Crohn's disease, and in 36 patients with ulcerative colitis. Excretion rates were correlated with clinical, serological, and endoscopic disease activity, disease extent, and location.

RESULTS

Urinary excretion of UMH was found to be significantly elevated in IBD. Patients with active Crohn's disease (7.1 +/- 4.2, p = 0.002 vs controls) and active ulcerative colitis (8.1 +/- 4.8, p = 0.02 vs controls) had higher rates of UMH excretion than patients in remission (6.3 +/- 3.8 and 5.2 +/- 2.3, respectively) or controls (4.6 +/- 1.9). In Crohn's disease and ulcerative colitis, a significant correlation of UMH excretion with clinical disease activity was obtained (Crohn's Disease Activity Index r2 = 0.58, Clinical Activity Index r2 = 0.57, p < 0.0001). Serologically, orosomucoid showed the best positive correlation with disease activity (Crohn's Disease Activity Index r2 0.80, Clinical Activity Index r2 = 0.86, p < 0.0001), but UMH excretion was found to reflect disease activity more accurately than C-reactive protein (Crohn's Disease Activity Index r2 = 0.46, Clinical Activity Index r2 = 0.42, p < 0.0001). No association between UMH excretion and disease type or localization could be found in Crohn's disease. However, UMH excretion correlated strongly with endoscopic severity of inflammation in Crohn's disease (Crohn's Disease Endoscopic Index of Severity r2 = 0.70, p < 0.0001) or disease extent in ulcerative colitis.

CONCLUSIONS

Urinary excretion of the histamine metabolite UMH is enhanced in IBD. It appears to represent an integrative parameter to monitor clinical and endoscopic disease activity in IBD, which appears to be influenced most likely by mediators released from histamine-containing cells, such as intestinal mast cell subtypes.

The role of C-reactive protein as a prognostic indicator in advanced cancer

C-reactive protein (CRP) is a nonspecific but sensitive marker of inflammation. Interleukin-6 (IL-6), IL-1, and tumor necrosis factor alpha induce the synthesis of CRP in hepatocytes. Increased CRP level is considered to be an important risk factor for atherosclerosis, myocardial infarction, peripheral vascular disease, and ischemic stroke. It is positively correlated with weight loss, anorexia-cachexia syndrome, extent of disease, and recurrence in advanced cancer. Its role as a predictor of survival has been shown in multiple myeloma, melanoma, lymphoma, ovarian, renal, pancreatic, and gastrointestinal tumors. Measurement of CRP is simple, cheap, and routine and provides valuable information in palliative care.

Histamine increases the expression of LOX-1 via H2 receptor in human monocytic THP-1 cells

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a member of the scavenger receptor family, and is known to be expressed in monocytes/macrophages. We investigated the effect of histamine on the expression of LOX-1 in cells of the human monocytic leukemia cell line THP-1. Histamine as well as forskolin and dibutyryl cyclic AMP (Bt2-cAMP) stimulated the THP-1 monocytes to express the LOX-1 gene at the transcription level. This histamine effect on LOX-1 gene expression, via the histamine H2 receptor-mediated cAMP signal transduction pathway, was reduced after differentiation of the cells into macrophages, even though forskolin and Bt2-cAMP still enhanced the gene expression. The alteration of the responsiveness of LOX-1 expression to histamine was related to suppressed expression of the H2 receptor in THP-1 macrophages. The switch of the predominant class of histamine receptors between H1 and H2 would modulate the effects of histamine on LOX-1 gene expression in monocytes and macrophages, and therefore, would play a certain role in the inflammatory aspects of atherogenesis.

Sunlight, immunosuppression and skin cancer: role of histamine and mast cells

1. The development into tumours of skin cells transformed by ultraviolet (UV) B radiation of wavelengths 290-320 nm is enhanced by the ability of UVB to suppress an immune response that would otherwise destroy them. Ultraviolet B-induced immunomodulation may be by multiple mechanisms, but generally manifests in an antigen-presenting cell defect and an altered cytokine environment in the draining lymph nodes. 2. Immune responses to microbial or self-antigens may be dysfunctional by similar mechanisms following UVB exposure. 3. Earliest-acting intermediates in the initiation of UVB-induced immunosuppression are the UVB absorbers (photoreceptors) of the skin, notably DNA resulting in immunoregulatory cytokine production, and trans-urocanic acid (UCA), which, upon isomerization to its cis isomer, signals downstream immunosuppressive events. 4. In mice, dermal mast cells are critical to UVB-induced systemic immunomodulation. In mice, there is a functional link as well as a linear relationship between the prevalence of histamine-staining dermal mast cells and the log of the dose of UVB required for 50% immunosuppression. Studies with histamine receptor antagonists support histamine as the main' product of mast cells involved. Histamine acts in large part via a prostanoid-dependent pathway. 5. Approximately 50% of humans and greater than 90% of patients with non-melanoma skin cancer are UVB susceptible for suppression of a contact hypersensitivity response. Neither cytokine polymorphisms nor UVB-induced levels of cis-UCA in irradiated skin have been linked to UVB susceptibility. Patients with basal cell carcinomas (BCC) have an increased dermal mast cell prevalence in non-sun-exposed buttock skin. We propose that mast cells function in humans, as in mice, by initiating immunosuppression and, thereby, allowing a permissive environment for BCC development.

Switch of histamine receptor expression from H2 to H1 during differentiation of monocytes into macrophages

It is known that histamine suppresses gene expression and synthesis of tumor necrosis factor alpha (TNF-alpha) induced by lipopolysaccharide (LPS) in human peripheral blood mononuclear monocytes (HPM) or alveolar macrophages via histamine H2 receptors. We investigated the effect of histamine and differentiation in macrophages on the expression and secretion of TNF-alpha, TNF-alpha-converting enzyme (TACE), and histamine H1 and H2 receptors by use of a leukemia cell line, U937, and HPM. Differentiation of U937 and HPM cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) enhanced the H1 receptor expression and rather suppressed the H2 receptor, resulting in up-regulation of the histamine-induced expression and secretion of TNF-alpha, modulated via TACE. Therefore, histamine failed to inhibit up-regulated expression of TNF-alpha induced by LPS in macrophages. The switch from H2 to H1 receptors during differentiation in the monocyte/macrophage lineage could participate in the pathogenic processes of atherosclerosis and inflammatory reactions in the arterial wall.

Histamine suppresses neopterin production in the human myelomonocytoma cell line THP-1

Histamine, an important inflammatory mediator in allergic diseases and asthma, was reported to have modulatory effects on T cells by down-regulating Th1-type cell cytokines like interleukin 2 (IL-2) and interferon-gamma (IFN-gamma). In this study we examined the effect of histamine and the histamine-receptor antagonists cimetidine and diphenhydramine on the production of neopterin after stimulation with IFN-gamma in the myelomonocytoma cell line THP-1. Increasing concentrations of histamine markedly suppressed IFN-gamma induced neopterin formation. Simultaneous preincubation of THP-1 cells with histamine, IFN-gamma and different concentrations of the H(2)-receptor antagonist cimetidine showed a clear antagonizing effect on neopterin formation. In contrast, the H(1)-receptor antagonist diphenhydramine was not able to abrogate the suppressive effect of histamine on neopterin production. Our results suggest, that histamine may be a potent inhibitor of effects or mechanisms induced by IFN-gamma in monocytes/macrophages. Cimetidine, and possibly other H(2)-receptor antagonists, may reverse down-regulatory actions of endogenously formed histamine on activated monocytic cells.

Validation of the internal reference technique for microdialysis measurements of interstitial histamine in the rat

The internal reference technique (IRT) was compared with the no net flux method (NFM) as a microdialysis calibration technique for sampling of interstitial histamine in the rat. Microdialysis catheters (polyacrylonitrile, 50 kD cut off) were inserted in liver, muscle, subcutaneous tissue and in an induced adenocarcinoma. Estimated relative recovery with IRT ranged from 23+/-2% in liver to 30+/-3% in subcutaneous tissue with and without tumor (p<0.05). By using the NFM-technique we found similar recovery as compared to the IRT in all tissues studied. Interstitial histamine was up to 3-fold higher than the mean plasma histamine concentration (54+/-2 nmol/l). Subcutaneous tissue (177+/-39 nmol/l) and subcutaneous tumor (165+/-29 nmol/l) exhibited high histamine while liver (65+/-14 nmol/l) and liver tumor (75+/-7 nmol/l) had low interstitial histamine concentrations. In conclusion, the IRT was validated against the NFM as a rapid method for histamine measurements in situ in the rat.

Virulizin(R) - A review of its antineoplastic activity

Virulizin(R) (registered trademark of Lorus Therapeutics, Inc.) is a novel biological response modifier (BRM) that enhances cell-mediated immune response to tumour cells by direct macrophage activation. The agent, an aqueous solution containing a 5% (w/v) solid material mixture comprised of inorganic salts (95 - 99% of the dry weight) and organic compounds of molecular weight < 3000 Daltons (1 - 5% of the dry weight), is provided as a sterile, injectable formulation. Virtually all the organic compounds and ionic components in the mixture have been identified by chemical and spectroscopic methods. Virulizin(R) is obtained from bovine bile by a standardised process involving solvent extraction and heat hydrolysis. In vitro studies have shown that Virulizin(R) can stimulate blood monocytes, peritoneal macrophages and alveolar macrophages from patients with malignant and non-malignant diseases to mediate a level of tumour cell cytolysis that is equal to, or greater than, that elicited in the same cells by other, more conventional biological activators. Other studies have shown that the stimulation of cytotoxic function by Virulizin(R) is insensitive to the inhibitory effects of prostaglandins and, hence, is distinct from many other activators. Furthermore, the blood monocytes of patients currently receiving cytotoxic chemotherapy showed activation with Virulizin(R). In preclinical studies, Virulizin(R) showed modest inhibition of tumour growth in a human pancreatic cancer xenograft model (T/C, 0.60; p = 0.012) and increased survival time by 8% (p = 0.046) in a murine melanoma model. Toxicity studies in rats indicated that Virulizin(R) injected intramuscularly was well-tolerated by the animals. Except for a lower rate of body weight gain in the high dose group, no toxicological effect related to treatment was observed in a chronic 13-week study (three weekly im. injections of up to 1.1 ml/kg). Mutagenicity studies with Virulizin(R) were negative. Many Phase I/II and Phase II clinical trials were carried out with Virulizin(R) to evaluate the safety and efficacy of the agent to treat cancer patients. Three of those studies involved the treatment of patients with pancreatic adenocarcinoma. The majority of patients participating in these studies were those who had failed conventional treatment including surgery or chemotherapy. Disease stabilisation was observed in patients treated with Virulizin(R), and, based on a meta-analysis of the data from the three studies, the survival of the patients treated with Virulizin(R) was better than a similar patient population receiving standard chemotherapeutic agent for that disease indication. However, randomised studies may be required to confirm the effect of Virulizin(R) on disease stabilisation and survival. In the three studies on patients with malignant melanoma, at least 69% treated with Virulizin(R) showed no additional deterioration or had improved at four weeks with response being only slightly reduced after eight weeks. In the evaluation of safety, assessed overall from these clinical studies in 200 patients treated with Virulizin(R), the number and severity of adverse events were small. In conclusion, Virulizin(R) is a novel, clinically non-toxic biological response modifier that appears to have a clinical effect on disease stabilisation and survival in patients with pancreatic cancer and malignant melanoma. However, additional randomised studies may be required to confirm those effects. Future studies on Virulizin(R) will focus on the characterisation of the active components in the agent and the development of a synthetic formulation. Subsequently, the preclinical and clinical pharmacokinetics of Virulizin(R) will be determined and studies to optimise the human dose of the agent will be carried out.

Mast cells mediate acute inflammatory responses to implanted biomaterials

Implanted biomaterials trigger acute and chronic inflammatory responses. The mechanisms involved in such acute inflammatory responses can be arbitrarily divided into phagocyte transmigration, chemotaxis, and adhesion to implant surfaces. We earlier observed that two chemokines-macrophage inflammatory protein 1alpha/monocyte chemoattractant protein 1-and the phagocyte integrin Mac-1 (CD11b/CD18)/surface fibrinogen interaction are, respectively, required for phagocyte chemotaxis and adherence to biomaterial surfaces. However, it is still not clear how the initial transmigration of phagocytes through the endothelial barrier into the area of the implant is triggered. Because implanted biomaterials elicit histaminic responses in the surrounding tissue, and histamine release is known to promote rapid diapedesis of inflammatory cells, we evaluated the possible role of histamine and mast cells in the recruitment of phagocytes to biomaterial implants. Using i.p. and s. c. implantation of polyethylene terephthalate disks in mice we find: (i) Extensive degranulation of mast cells, accompanied by histamine release, occurs adjacent to short-term i.p. implants. (ii) Simultaneous administration of H1 and H2 histamine receptor antagonists (pyrilamine and famotidine, respectively) greatly diminishes recruitment and adhesion of both neutrophils (<20% of control) and monocytes/macrophages (<30% of control) to implants. (iii) Congenitally mast cell-deficient mice also exhibit markedly reduced accumulation of phagocytes on both i.p. and s.c implants. (iv) Finally, mast cell reconstitution of mast cell-deficient mice restores "normal" inflammatory responses to biomaterial implants. We conclude that mast cells and their granular products, especially histamine, are important in recruitment of inflammatory cells to biomaterial implants. Improved knowledge of such responses may permit purposeful modulation of both acute and chronic inflammation affecting implanted biomaterials.

Signaling and functional properties of interleukin-16

Interleukin-16 is secreted from a variety of immune cells as a peptide of 17 kDa which aggregates into tetrameric form essential for IL-16s direct interaction with and cross linking of its receptor, the CD4 antigen. IL-16 stimulation of CD4+ cells results in the induction of cell motility, and in addition can function as a competence growth factor for CD4+ lymphocytes. These activities suggest that IL-16 could play a role in the accumulation and activation of CD4+ cells recruited to sites of inflammation. Along those lines, IL-16 has been identified at sites of inflammation associated with several different disease states. Its function as a competence growth factor specifically for CD4+ T cells may be useful for immune reconstitution in immunodeficiency diseases such as AIDS.

Systemic T-cell unresponsiveness during rush bee-venom immunotherapy

By rush bee-venom immunotherapy, subjects reacting allergically to the venom can be effectively anergized, although the mechanism of action is not known. Here we analyzed the systemic effects of rush desensitization on the T cells of allergic patients. In most patients, we found reduced frequencies of T cells recalled to express CD69 and the cytokines interleukin (IL)-4 and interferon-gamma (IFN-gamma) after stimulation of peripheral blood mononuclear cells with phorbol 12-myristate 13-acetate (PMA) and ionomycin, as compared with normal donors. These frequencies are progressively reduced during immunotherapy. The frequency of cells expressing IL-2 does not change. A few patients show a different response to immunotherapy: frequencies of cells expressing CD69, IL-4, or IFN-gamma do not change, and remain similar to those of normal donors. However, the frequency of cells able to express IL-2 is increased. The analysis of cytokine expression in CD45RO+ vs CD45RO- T-cell populations revealed differences between normal and allergic donors. In allergic patients, higher frequencies of IL-4- and IFN-gamma-expressing cells among the CD45RO- subpopulation were found than in normal donors. This situation is not modified by immunotherapy. The results reveal a certain degree of heterogeneity in the response of allergic patients to bee-venom rush immunotherapy; however, all are clearly differentiated from normal controls as judged by cytokine expression of CD45RO- T cells. In most allergic patients, a considerable percentage of Th cells become unresponsive to mitogenic stimulation, and may be responsible for the desensitization itself.

Tetrandrine potently inhibits herpes simplex virus type-1-induced keratitis in BALB/c mice

This study investigated the effect of tetrandrine (TDR) on experimental herpes simplex keratitis (HSK) in mice. BALB/c mice were divided as follows: Group 1, untreated; Group 2, acyclovir (ACV)-treated from day 0 postinfection; Group 3, ACV-treated from day 7; Group 4, TDR-treated from day 0; and Group 5, TDR-treated from day 7. All mice were infected in the right cornea with herpes simplex virus (HSV) type I. TDR 30 mg/kg and ACV 120 mg/kg were administered intraperitoneally daily. The mice were observed for 14 days postinfection. Clinical inflammatory reactions and ocular histopathology were analyzed. The herpes specific antibody response and the delayed type hypersensitivity (DTH) response were studied. Of the 22 untreated mice, 16 developed HSK (incidence, 72.7%). TDR given from day 7 reduced the HSK incidence to 8.5% (p < 0.01); the incidence of HSK was 45.4% in mice treated with TDR from day 0 (p > 0.05). Systemic ACV given from day 0 inhibited HSK development (p < 0.01); ACV given from day 7 resulted in an HSK incidence of 50% (p > 0.05). The specific anti-HSV antibody response in the serum of mice treated with TDR or ACV either from day 0 or day 7 was significantly less than that of untreated mice (p < 0.01 and p < 0.05, respectively), and TDR treatment suppressed DTH responses to HSV (p < 0.05). Systemic TDR administered after HSV inoculation of the cornea significantly modulates murine HSK development at least partly by modifying the host immune/inflammatory response to the virus.

Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults

OBJECTIVE

The purpose of this study was to determine whether carnitine metabolism or histamine degradation would be useful parameters for investigating the optimal requirement for vitamin C.

METHODS

Twenty-two non-scorbutic subjects with subnormal vitamin C status (plasma vitamin C < 28 mumol/L) were placed on a metabolic diet low in vitamin C for 3 weeks and repleted with graded doses of vitamin C: 10, 30 and 60 mg vitamin C daily (group 1) or 10,125 and 250 mg vitamin C daily (group 2) for weeks 1, 2 and 3, respectively. Fasting blood samples were collected weekly and analyzed for plasma vitamin C, plasma free carnitine and blood histamine.

RESULTS

Group 1 subjects remained in a subnormal vitamin C state throughout the 3-week study, and blood histamine and plasma free carnitine were not impacted by the experimental treatment. Plasma vitamin C in group 2 subjects rose significantly during the study, and these subjects finished the study with an ample vitamin C status indicative of vitamin C intakes above the recommended dietary allowance. Both blood histamine and plasma free carnitine were inversely related to vitamin C status in group 2 subjects.

CONCLUSIONS

These data indicate that blood histamine and plasma free carnitine are altered in individuals with subnormal, non-scorbutic vitamin C status and provide evidence that metabolic changes independent of collagen metabolism occur prior to the manifestation of scurvy. Thus utilizing scurvy as an end-point to determine vitamin C requirements may not provide adequate vitamin C to promote optimal health and well-being.

Interactions between endothelial cells and effector cells in allergic inflammation

The local inflammatory response that occurs after repeated exposure to allergens or during the late-phase reaction results from a complex network of interactions between inflammatory cells (mast cells, eosinophils, macrophages) and resident cells belonging to the lung structure itself like EC, fibroblasts, or bronchial epithelial cells. Among structural cells, EC represent critical elements: they control leukocyte traffic through the expression of adhesion molecules; they are also able to amplify leukocyte activation through the production of proinflammatory cytokines like IL-1, IL-6, or of chemokines like IL-8. Three cell models have been successively considered. When supernatants of alveolar macrophages, recovered from patients exhibiting a late asthmatic response after allergen exposure, were tested on HUVEC cultures, a TNF alpha-dependent ICAM-1 and E-selectin overexpression was observed. Among mast-cell mediators, histamine was already known to induce a rapid and transient expression of P-selectin; we demonstrated that histamine also induced an IL-6 and IL-8 secretion by HUVEC, which was concentration-dependent and inhibited by H1 or H2 receptor antagonists. Finally purified eosinophils obtained from donors with hypereosinophilia similarly increased adhesion molecule expression and chemokine production. The precise nature of the eosinophil product(s) involved in this process is currently under investigation.

Histamine-2 receptor antagonists as immunomodulators: new therapeutic views?

Considerable evidence has emerged to suggest that histamine participates in the regulation of the inflammatory response, immune reaction, coagulation cascade, and cardiovascular function. Furthermore, histamine may play a major role in the growth of normal and malignant tissue as a regulator of proliferation and angiogenesis. Specific histamine receptors have been identified on the surface of bone marrow cells, immune competent cells, endothelial cells, fibroblasts, and also on malignant cells. This has prompted research in regulation by specific histamine receptor agonists and antagonists. Results from such studies are currently accumulating and suggest that the histamine-2 receptor antagonists have potential beneficial effects in the treatment of certain malignant, autoimmune and skin diseases, either alone or in combination with other drugs. The beneficial effect of histamine-2 receptor antagonists as adjuvant single drugs to reduce trauma-, blood transfusion- and sepsis-induced immunosuppression has led to research in combined treatment regimens in major surgery, particularly, of patients operated on for malignant diseases.

In vitro effect of cetirizine on PGE2 release by rat peritoneal macrophages and human monocytes

Cetirizine was first described as a specific anti-H1 molecule displaying potent antiallergic activity. It was later found that its pharmacological properties extended to cellular actions as on eosinophil recruitment at inflammatory sites in allergic patients. Monocytes and macrophages participate in allergic mechanisms, particularly through high affinity H1 and H2 membrane receptors and generation of pro- and anti-inflammatory agents; among them histamine-induced factors, IL-1 and prostanoids are of importance. The aim of this work was to investigate the effect exerted by various concentrations of cetirizine (0.1-10 micrograms/ml) applied in vitro to human monocytes and peritoneal rat macrophages cultured for 24 h. Peritoneal macrophages were collected either from normal or experimentally inflamed rats. Human monocytes, isolated from peripheral blood, were studied either in a resting state or after stimulation by LPS from Escherichia coli (1 and 10 micrograms/ml). Cetirizine (10 micrograms/ml) significantly enhanced IL-1 release by human monocytes stimulated by a weak LPS concentration (1 microgram/ml) but could not modify the maximal increase of IL-1 release induced by 10 micrograms/ml of LPS. It did not exert any effect on resting cells. Cetirizine (0.1-10 micrograms/ml) enhanced PGE2 release by resting human monocytes. Concentrations of 1 and 10 micrograms/ml enhanced PGE2 release by LPS-stimulated monocytes, and by healthy and inflamed rat macrophages. This effect was concentration-dependent. Our findings point to an anti-inflammatory action of cetirizine via PGE2 release and histamine H2 interactions. Cetirizine did not directly modify IL-1 generation by resting monocytes but the IL-1 production observed after LPS stimulation could promote the mechanisms by which PGE2 is released.

Effect of seven new vasoactive immunoconjugates on the enhancement of monoclonal antibody uptake in tumors

BACKGROUND

To enhance monoclonal antibody uptake in tumors, seven novel vasoactive immunoconjugates were developed that selectively alter the vascular permeability and/or blood volume of tumors in vivo. These immunoconjugates, composed of IL-1 beta, IL-2, TNF-alpha, physalaemin, leukotriene B4, histamine, and bradykinin chemically linked to TNT-1, a murine monoclonal antibody that binds necrotic regions in tumors, have been tested for their effects on antibody uptake in vivo.

METHODS

Groups of four mice, each bearing the ME-180 human cervical carcinoma, were pretreated either 3 or 24 hours before the administration of I-125 labeled TNT-1 F(ab')2 fragment. Three-day biodistribution studies then were performed to determine the amount of radiolabeled antibody in the tumors and normal organs of the mice. In addition, mechanism of action studies were performed to determine if the vasoactive immunoconjugate affected the vascular permeability or blood volume of the tumor vessels.

RESULTS

TNT-1/IL-2 gave the highest percent injected dose/g in tumor (4.80), compared with TNT-1/TNF (4.00), TNT-1/IL-1 (3.83), TNT-1/leukotriene-B4 (2.84), TNT-1/histamine (2.80), TNT-1/physalaemin (2.19), TNT-1/bradykinin (1.57), or TNT-1 alone (1.28). All of these immunoconjugates showed specific enhancement of monoclonal antibody uptake in tumor with no changes seen in normal tissues. Quantitative studies that demonstrated the mechanism of action of these immunoconjugates showed that TNT-1/IL-2 and TNT-1/histamine produced a marked change in the vasopermeability of tumor vessels but had no effect on tumor blood volume. In contrast, TNT-1/IL-1 and TNT-1/TNF produced a combination of effects, and TNT-1/leukotriene B4, TNT-1/bradykinin, and TNT-1/physalaemin affected only tumor blood volume.

CONCLUSIONS

These studies indicate that pretreatment with vasoactive immunoconjugates may improve monoclonal antibody uptake in tumors significantly and thereby increase the therapeutic index of monoclonal antibody-directed immunotherapy.

Activation by histamine of bronchial epithelial cells from nonasthmatic subjects

Histamine is a major mediator of the mast cells that are present between epithelial cells in asthma. In asthma, there is an increased expression of ICAM-1 and HLA-DR and an increased spontaneous release of fibronectin. The effect of histamine was tested on bronchial epithelial cells obtained by bronchial brushing from 22 nonasthmatic subjects. The activation of epithelial cells was assessed by immunocytochemical analysis of the expression of membrane markers (ICAM-1 and HLA-DR) using the alkaline phosphatase-anti-alkaline phosphatase method and the release of fibronectin (enzyme immunoassay). Time-response (three experiments) and dose-response (six experiments) curves showed that the maximal effect was obtained after an incubation time of 24 h and a dose of 1 microM of histamine. For this time course and concentration, there was a highly significant increase in the number of cells expressing ICAM-1 (before histamine: 10 +/- 11%; after histamine: 32 +/- 20%; P < 0.001) and HLA-DR (before histamine: 8 +/- 7%; after histamine: 23 +/- 20%; P < 0.001) and in the release of fibronectin (before histamine: 30 +/- 20 ng/10(5) viable cells; after histamine: 61 +/- 35 ng/10(5) viable cells; P < 0.003). Cycloheximide blocked these effects, suggesting that histamine requires protein synthesis for its action. Pyrilamine (H1-blocker) and ranitidine (H2-blocker) at a concentration of 10 microM decreased the effect of histamine. However, there was no additive effect when both antagonists were added. This study suggests that mast cells present in the airways have a role in the activation of epithelial cells.

Inhibitory effect of azelastine, a potent antiallergic agent, on release of tumor necrosis factor-alpha from activated human peripheral blood mononuclear cells and U937 cells

It is generally accepted that tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine which is involved in the regulation of inflammation as well as immunity. In the present study, we investigated whether azelastine, a potent antiallergic agent, affects release of TNF-alpha from peripheral blood mononuclear cells (PBMC) and U937 cell line in vitro. When human PBMC and U937 cells were stimulated by phytohemagglutinin (PHA) and 12-0-tetradecanoyl-phorbol-13-acetate (TPA), respectively, the cells released significant amounts of TNF-alpha as determined by TNF-alpha-specific enzyme immunoassay. TNF-alpha levels in the culture supernatant of PHA-stimulated human PBMC and TPA-activated U937 cells decreased in a dose-dependent manner when these cells were cultured in the presence of azelastine. This inhibitory effect of azelastine was obtained at concentrations where the drug produced no toxicity. Moreover, azelastine also inhibited release of TNF-alpha from U937 cells which were already activated by TPA. These results suggest that the inhibitory effect of azelastine on TNF-alpha release plays an important role in its antiallergic action in addition to inhibition and/or antagonism of histamine and leukotrienes, which has been previously reported.

Inhibition of prostaglandin E2 formation and histamine action in cancer immunotherapy

The activity of cell-mediated defense systems is stimulated by consecutive formation of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2) and interferon gamma (IFN gamma). The system is inhibited by interleukin-4 (IL-4) and also by prostaglandin E2 (PGE2) and histamine, which are released when the immune system is activated. The inhibition is strong in cancer patients, because PGE2 is formed in many cancer cells and its formation is stimulated by IL-1 beta. The release of histamine is also stimulated by IL-1 beta. Thus PGE2 and histamine are feedback inhibitors of cell-mediated immunity. This inhibition can be abolished by inhibitors of the cyclo-oxygenase (e.g. indomethacin) and H-2 receptor antagonists (e.g. cimetidine). This may offer a new option to stimulate the immune system to kill cancer cells.

Differential expression of CR3, Fc epsilon RII and Fc gamma RIII on polymorphonuclear leukocytes in gingival crevicular fluid

Polymorphonuclear leukocytes (PMNLs) are the most numerous cell population among the cellular infiltrates in gingival crevicular fluid (GCF) and play important roles in the host-defensive system in the gingival crevices. We determined the percentage of neutrophils, eosinophils and basophils in total PMNLs by light microscopic observation using Randolph-methylene blue staining, then assessed flow cytometric differences in the expression of CR3, Fc gamma RIII, Fc epsilon RII, LFA-1 alpha, and LFA-1 beta on PMNL in GCF and peripheral blood (PB) from 21 patients with adult periodontitis (AP) and 13 healthy donors. Percentages of basophils and eosinophils were higher in GCF than in PB. In both AP patients and healthy subjects, expression of CR3 and Fc epsilon RII was higher while Fc gamma RIII was lower in GCF than in PB. The statistical analysis showed that the expressions of Fc gamma RIII and Fc epsilon RII on GCF PMNLs were lower in AP patients than in healthy subjects. Expressions of LFA-1 alpha and beta on GCF were similar to those on PB PMNLs. PB PMNLs stimulated in vitro with Porphyromonas gingivalis culture supernatant and fMLP displayed an expression pattern of CR3, Fc gamma RIII and Fc epsilon RII on GCF PMNLs. However, C5a and IL-1 failed to induce changes in Fc gamma RIII and Fc epsilon RII. The results indicate that GCF neutrophils are activated, present enhanced adhesion and a decreased IgG-binding ability which would reflect that they are at the terminal stage of activation, and that GCF contains a larger eosinophil fraction than in PB. Moreover, these GCF eosinophils appear to be activated.

Histamine and cis-urocanic acid augment tumor necrosis factor-alpha mediated induction of keratinocyte intercellular adhesion molecule-1 expression

Early cellular and molecular events in inflamed skin include the active participation of epidermal keratinocytes (KCs) and dermal mast cells which can produce diffusible mediators such as tumor necrosis factor-alpha (TNF-alpha), histamine, and urocanic acid (UCA). Rapid induction of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) by KCs is observed following a highly diverse array of stimuli which can provoke both irritant, inflammatory, as well as allergic and immune reactions. To determine if the aforementioned mediators could interact in either an additive or synergistic fashion with each other, cultured KCs were exposed to these mediators alone and in combination, and the degree of ICAM-1 mRNA and protein quantitated. Whereas histamine or cis-UCA alone only weakly induced KC ICAM-1, when they were combined with TNF-alpha, significant augmentation was observed by Northern blot hybridization studies, immunostaining, and FACS analysis. Other histamine derivatives such as L-histidine, 1-methylhistidine, 3-methylhistidine, or all-trans-UCA had no effect. Histamine pretreatment did not affect cell surface high affinity TNF-alpha receptors, as determined by ligand binding and immunodetection, and did not induce KC TNF-alpha production. The KC histamine receptor was also characterized and found not to be influenced by TNF-alpha, cis-UCA, all-trans-UCA, or diphenhydramine (an H1 antagonist), but it was inhibited by cimetidine (an H2 antagonist). These results demonstrate that 1) KCs can be induced to express ICAM-1 by exposure to histamine and cis-UCA, 2) histamine and cis-UCA can also augment TNF-alpha inducible ICAM-1 mRNA and cell surface protein expression, 3) this augmentation does not directly involve changes in KC TNF-alpha receptor number, affinity, or TNF-alpha production and, 4) KCs possess a type 2 histamine receptor which is not the photoreceptor for UCA. These findings highlight the potential for cross-talk between molecules produced by resident cutaneous cell types above (i.e., KCs) and below (i.e., mast cells) the epidermal basement membrane zone. These cells and their mediators can cooperate to respond to either exogenous or endogenous stimuli leading to rapid and strong KC ICAM-1 expression. Such induction of this important adhesion molecule by KCs ensures the retention of T lymphocytes necessary to participate in the maintenance of cutaneous immunohomeostasis.

Allergic disorders in systemic lupus erythematosus

Allergic disorders commonly occur in patients with systemic lupus erythematosus (SLE) and allergies to some drugs may occasionally be related to disease flares. We evaluated the prevalence of several types of allergy in 132 patients with SLE and their families and compared the SLE patients with a control group of 66 patients with non-lupus disorders. Total IgE levels were tested in 117 SLE patients and 61 controls. Eighty-three of the 132 SLE patients (63%) had a history of at least one type of allergic disorder. This prevalence was significantly higher (P < 0.0001) than that of the control group (20 of 66 controls). The prevalence of drug allergy (38% vs. 17%; P < 0.005), skin allergy (36% vs. 17%; P < 0.01) and insect allergy (14% vs. 2%; P < 0.02) were significantly higher in SLE patients when compared with controls. Family members of SLE patients had an increased prevalence of at least one type of allergy (55% vs. 24%; P < 0.0001), allergic rhinitis (30% vs. 14%; P < 0.02), asthma (25% vs. 9% P < 0.02), and both rhinitis or asthma (44% vs. 20%; P < or = 0.002). The presence of allergy both in the patient and in the family was more frequent in SLE patients than controls (42% vs. 15%; P < 0.001). We found no differences in total IgE levels between the two groups. Drug, skin and insect allergies were particularly frequent in SLE patients. We also found a high prevalence of rhinitis and asthma in their families.

Role of cAMP in regulating cytotoxic T lymphocyte adhesion and motility

We investigated the functional role of the cAMP pathway in human cytotoxic T lymphocyte (CTL)-target interaction. Pharmacological increase of intracellular cAMP concentration ([cAMP]i) inhibits killing, especially at low effector-to-target ratios, suggesting an inhibitory effect on CTL recycling. We show that this inhibitory effect is primarily at the level of conjugate formation. Pharmacological increase in [cAMP]i, as well as treatment with cytochalasin D, results in a "rounding up" of the CTL and inhibition of the dramatic changes in shape that occur when a CTL forms a conjugate, even with an irrelevant target. In addition, pharmacological increase in [cAMP]i affects the cytoskeleton of the CTL since it induces a decrease of filamentous actin, as detected by flow cytometry on phalloidin-stained CTL, and a stabilization of microtubules, as detected by increased resistance to the disrupting action of nocodazole. In mature CTL (but not in their immature precursors), T cell receptor triggering by specific targets results in a measurable increase in cAMP levels and strongly synergizes with adenylyl cyclase activators such as prostaglandin E2, cholera toxin and forskolin. We suggest that T cell receptor triggering may induce accumulation of cAMP that interferes with cytoskeleton function and, thus, terminates CTL secretion and adhesion. These effects of cAMP are rapidly reversible and may regulate CTL recycling.