Clinical symptom tool that raises the index of suspicion for eosinophilic oesophagitis in adults and drives earlier biopsy for definitive diagnosis.

BACKGROUND: Eosinophilic oesophagitis (EoE) and gastro-oesophageal reflux disease (GERD) present with overlapping symptomatology and it is challenging to distinguish EoE from GERD clinically before endoscopy. AIM: To investigate the prognostic value of a set of clinical symptoms and laboratory values in patients with EoE and GERD. METHODS: In this prospective, single-centre, observational study, we compared clinical and laboratory data from 202 patients with EoE or GERD (10 relevant characteristics). Those characteristics showing potential significance in a univariate analysis were then included in a multivariate analysis. RESULTS: The set of 10 characteristics (10-marker set) was able to distinguish between EoE and GERD with good reliability (correct assignment, i.e. agreement with subsequent EGD, of 94.4%). Reduction of the set to the six statistically and clinically most relevant markers continued to give good reliability (88.9%), and further stepwise reduction led to four-marker sets comprising history of atopy, history of food impaction, proton pump inhibitor refractory symptoms and either immunoglobulin E or peripheral eosinophilia, with correct assignment rates of 91.3% and 85.1% respectively. CONCLUSIONS: We have developed a simple and easily applicable clinical/laboratory marker set that helps to distinguish EoE from GERD earlier in the treatment course, thus guiding the endoscopist to perform biopsies from the oesophagus to ensure the diagnosis. The application of the scoring system is expected to diagnose EoE earlier and avoiding delay of adequate treatment.

Autoimmunity in Crohn's Disease-A Putative Stratification Factor of the Clinical Phenotype.

Inflammation in inflammatory bowel diseases (IBD) has been linked to a loss of tolerance to self-antigens suggesting the existence of autoantibodies in specific disease phenotypes. However, the lack of clearly defined autoantigenic targets has slowed down research. Genome-wide association studies have identified an impressive number of immune-related susceptibility loci for IBD with no clearly discernible pattern among them. Growing evidence supports the hypothesis that innate immune responses to a low-diversity and impaired gut microbiota may be of key importance in initiating and perpetuating chronic inflammation in IBD. Increasing evidence suggests that reduced microbial diversity and microbial-mucosal epithelium interaction (including adhesion and clearance) are critically involved in IBD pathogenesis. Along these lines the discovery of autoantigenic targets in Crohn's disease (CD) has refocused research in IBD on the possible role of autoimmune responses. The identification of the major zymogen granule membrane glycoprotein 2 (GP2) as an autoantigen in CD patients and its proposed role in the sensing of the microbiota lends credence to this trend. Loss of tolerance to GP2 occurs in up to 40% of patients with CD. Corresponding autoantibodies appear to be associated with distinct disease courses (types or phenotypes) in CD. Here, we critically review autoantibodies in CD for their impact on clinical practice and future IBD research. The immunomodulatory role of GP2 in innate and adaptive intestinal immunity is also discussed.

Autoimmune gastritis in autoimmune thyroid disease.

BACKGROUND: Autoimmune gastritis leads to oxyntic gastric atrophy, a condition at increased risk for gastric cancer. Autoimmune gastritis in conjunction with autoimmune thyroid disease has been reported previously. AIM: In a case-control study in patients with autoimmune thyroid disease to evaluate the usefulness of serum pepsinogens for the identification of oxyntic gastric atrophy, and to determine the relationship of Helicobacter pylori with oxyntic gastric atrophy. METHODS: Patients with autoimmune thyroid disease (cases) and goitre (controls) were prospectively enrolled in the study. Pepsinogen (PG) I levels ≤25 µg/mL and PG I/II ratio ≤3 were indicative for oxyntic gastric atrophy. Antibodies against H. pylori, CagA and parietal cells were also determined. Esophagogastroduodenoscopy with biopsies was offered to patients with serological oxyntic gastric atrophy. RESULTS: In total, 34 autoimmune thyroid disease patients and 30 controls were enrolled. Serological oxyntic gastric atrophy was present only in autoimmune thyroid disease patients (8/34, 23.5%, OR 8.3, 95% CI = 1.9-36.2). In all eight patients oxyntic gastric atrophy was confirmed by histology. OLGA stage I, II, III and IV was described in 0%, 33%, 50% and 17% of the cases, respectively. About, 89% and 11% of oxyntic gastric atrophy patients were seropositive for antibodies against parietal cells or H. pylori infection, respectively. Gastric atrophy involved the angulus/antrum in 50% of patients with autoimmune gastritis. CONCLUSIONS: The seroprevalence of oxyntic gastric atrophy is high in patients with autoimmune thyroid disease, and testing of serum pepsinogens should be included in the clinical assessment of these patients. H. pylori infection is unlikely to be a principal factor in the pathogenesis of oxyntic gastric atrophy in patients with autoimmune thyroid disease. In autoimmune gastritis, gastric atrophy can spread from the oxyntic towards the antral mucosa.

Constitutive expression of murine c-FLIPR causes autoimmunity in aged mice.

Death receptor-mediated apoptosis is a key mechanism for the control of immune responses and dysregulation of this pathway may lead to autoimmunity. Cellular FLICE-inhibitory proteins (c-FLIPs) are known as inhibitors of death receptor-mediated apoptosis. The only short murine c-FLIP splice variant is c-FLIPRaji (c-FLIPR). To investigate the functional role of c-FLIPR in the immune system, we used the vavFLIPR mouse model constitutively expressing murine c-FLIPR in all hematopoietic compartments. Lymphocytes from these mice are protected against CD95-mediated apoptosis and activation-induced cell death. Young vavFLIPR mice display normal lymphocyte compartments, but the lymphocyte populations alter with age. We identified reduced levels of T cells and slightly higher levels of B cells in 1-year-old vavFLIPR mice compared with wild-type (WT) littermates. Moreover, both B and T cells from aged vavFLIPR animals show activated phenotypes. Sera from 1-year-old WT and transgenic animals were analysed for anti-nuclear antibodies. Notably, elevated titres of these autoantibodies were detected in vavFLIPR sera. Furthermore, tissue damage in kidneys and lungs from aged vavFLIPR animals was observed, indicating that vavFLIPR mice develop a systemic lupus erythematosus-like phenotype with age. Taken together, these data suggest that c-FLIPR is an important modulator of apoptosis and enforced expression leads to autoimmunity.

Treatment of severe autoimmune blistering skin diseases with combination of protein A immunoadsorption and rituximab: a protocol without initial high dose or pulse steroid medication.

BACKGROUND: Skin blistering diseases due to autoantibodies are typically treated with high dose systemic corticosteroids and other conventional immunosuppressants. However, in severe cases, this treatment may not be sufficient to achieve disease control or contraindicated because of comorbidity. METHODS: We describe 15 patients (pts.) with such diseases: 6 pts. with pemphigus vulgaris, 3 pts. with bullous pemphigoid, 3 pts. with mucous membrane pemphigoid (MMP), one being anti-laminin-332-MMP (AL332-MMP), 2 pts. with pemphigus foliaceus and 1 pt. with epidermolysis bullosa acquisita (EBA). Patients were treated with a combination of protein A immunoadsorption (PAIA, 3-21 treatments) and rituximab (3-6 treatments) in addition to low dose conventional immunosuppression. RESULTS: All patients showed rapid clinical improvement starting within the first 4 weeks and decline of circulating autoantibody levels. Complete/partial remission was 88%/12% in pemphigus and 71%/29% in subepidermal blistering diseases. Overall relapse rate was 13% with an average follow-up of 22 months. In the AL332-MMP pt. the PAIA/rituximab treatment was stopped because of an oesophagus cancer considered as the paraneoplastic cause of the skin disease. CONCLUSION: Combined treatment with PAIA and rituximab showed rapid and long-lasting response, thereby allowing substantial reduction of dosage of concomitant immunosuppressive medication. We hereby confirm data from other investigators that PAIA/rituximab treatment is a promising therapeutical modality for pemphigus, pemphigoids and EBA, characterized by a favourable ratio of beneficial efficacy and minimized long-term adverse effects.

[Human leukocyte antigen (HLA) system in ophthalmology]. / Humanes Leukozytenantigensystem in der Augenheilkunde.

Various inflammatory and non-inflammatory eye diseases are associated with specific HLA isotypes. Therefore, HLA isotyping can be a useful diagnostic tool for these diseases and has already been shown to reduce the rejection rate of corneal allografts. Unfortunately, the volume of published data and the varying quality of these publications complicate obtaining good overview in this field. This review briefly summarizes the genetic structure of the HLA system and elucidates differences between HLA classes I and II in the context of antigen presentation. Possible mechanisms of HLA associations in the field of ophthalmology are discussed, and finally different tools (e.g. genome wide association studies) for assessing associations of HLA isotypes with different ocular diseases are examined.

The digital MIQE guidelines: Minimum Information for Publication of Quantitative Digital PCR Experiments.

There is growing interest in digital PCR (dPCR) because technological progress makes it a practical and increasingly affordable technology. dPCR allows the precise quantification of nucleic acids, facilitating the measurement of small percentage differences and quantification of rare variants. dPCR may also be more reproducible and less susceptible to inhibition than quantitative real-time PCR (qPCR). Consequently, dPCR has the potential to have a substantial impact on research as well as diagnostic applications. However, as with qPCR, the ability to perform robust meaningful experiments requires careful design and adequate controls. To assist independent evaluation of experimental data, comprehensive disclosure of all relevant experimental details is required. To facilitate this process we present the Minimum Information for Publication of Quantitative Digital PCR Experiments guidelines. This report addresses known requirements for dPCR that have already been identified during this early stage of its development and commercial implementation. Adoption of these guidelines by the scientific community will help to standardize experimental protocols, maximize efficient utilization of resources, and enhance the impact of this promising new technology.

[Old immune system- new information? Importance of mononuclear phagocytes in corneal allograft rejection]. / Altes Immunsystem - Neue Erkenntnisse? : Bedeutung mononukleärer Zellen bei der allogenen Hornhauttransplantatabstoßung.

Mononuclear phagocytes are derived from bone marrow precursor cells and are part of the innate immune system. These cells circulate in the blood as monocytes but differentiate in the peripheral circulation into tissue macrophages and dendritic cells under the influence of various cytokines. In addition to antimicrobial properties, macrophages also participate in wound healing; however, they also support degenerative and inflammatory processes. In cases of acute corneal allograft rejection, mononuclear cells initially form the main component of the cellular anterior chamber infiltrate. How monocytes are recruited into the anterior chamber is currently uncertain. Furthermore, no information is available about the possible cytotoxic effects on corneal endothelial cells. Gaining insight into these mechanisms may lead to potential pharmacological interventions.

Progressive lipo-lymphedema associated with increased activity of dermal fibroblasts in monoclonal gammopathy of undetermined significance: is there a causal relationship?

The pathophysiology of skin diseases associated with monoclonal gammopathies is generally unknown. Our aim was to investigate whether a monoclonal gammopathy could be a causal factor in progressive lymphedema. We describe a 75 year old patient with a rapidly progressive lipo-lymphedema and a monoclonal gammopathy of unknown significance (MGUS) suspected as a key etiological factor. Dermal fibroblasts were cultured from lesional lower leg skin and non-lesional abdominal skin and compared to healthy control fibroblasts. We found 10-fold elevated basic fibroblast growth factor 2 (FGF-2) in the patient's serum and significantly increased basal FGF-2 production of lesional and non-lesional fibroblasts compared to healthy controls. Upon restimulation with patient or healthy control serum, lesional fibroblasts showed significantly increased proliferation rates and FGF-2 production in vitro. Non-lesional abdominal fibroblasts showed an intermediate phenotype between lesional and control fibroblasts. Our findings provide the first evidence that lesional dermal fibroblasts from lipo-lymphedema with plasma cell infiltration show increased proliferation and FGF-2 production and that both local tissue factors and altered FGF-2 serum levels associated with monoclonal gammopathies might contribute to this phenotype. Thus we propose a possible pathophysiologic link between the gammopathy-associated factors and the generation of lymphedema with initial fibrogenesis aggravating pre-existing lipedema.

Pro-inflammatory effector Th cells transmigrate through anti-inflammatory environments into the murine fetus.

The presence of maternal DNA or even maternal cells within the offspring (microchimerism) has been reported for many fetal tissues, including the liver, heart, and spleen. Microchimerism is believed to be involved in the pathogenesis of autoimmune diseases; however, the cellular origin of this phenomenon remains unknown. Here, we determined whether differentiated T lymphocytes could transmigrate through the immunosuppressive environment of the placenta to reach the fetus. In vitro-differentiated effector/memory Th1 and Th17 cells from OVA323₋339-specific TCR(tg) T cells of OT-II mice were adoptively transferred (i.v.) into the tail veins of pregnant Ly5.1 mice at d15 and d19 of gestation. Mice were then sacrificed 40 h after adoptive cell transfer. Using radioactive labeling of T cells with sodium chromate [Cr5¹] prior to adoptive transfer, we observed that homing of pro-inflammatory Th cells was equally efficient in both pregnant and non-pregnant mice. Transmigration of Th1- and Th17-like cells through the highly immunosuppressive environment of the placenta into the fetus was significantly enhanced in experimental mice compared to control mice (P < 0.0001). In addition, a substantial amount of effector Th cells accumulated in the placenta. Finally, we found that treatment with Pertussis Toxin resulted in a 3-fold increase in the transmigration of effector Th17 cells into the fetus (P < 0.0001). When pro-inflammatory Th1-or Th17-like cells were injected into syngeneic mothers, almost all of the fetuses analyzed exhibited radioactivity, suggesting that transmigration of effector T cells occurs frequently. Our results suggest the possibility of novel roles for these maternal effector cells in the pathogenesis or reduction of disease.

Identification of GP2, the major zymogen granule membrane glycoprotein, as the autoantigen of pancreatic antibodies in Crohn's disease.

BACKGROUND AND AIMS: The aetiopathogenesis of Crohn's disease, an inflammatory bowel disease (IBD), is not yet fully understood. Autoimmune mechanisms are thought to play a role in the development of Crohn's disease, but the target antigens and the underlying pathways have not been sufficiently identified. METHODS: Based on data from immunoblotting and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry, the major antigenic target of pancreatic autoantibodies (PABs), which are specific for Crohn's disease, was identified. Specificity of autoantibody reactivity was confirmed by enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (IIF) using purified rat and human recombinant GP2 synthesised in transiently transfected mammalian HEK 293 cells. Real-time polymerase chain reaction (rt-PCR) and IIF were used to detect mRNA and antigen localisation in human colon biopsies. RESULTS: The major zymogen granule membrane glycoprotein 2 (GP2) was identified as the autoantigen of PABs in Crohn's disease. PAB-positive sera from patients with Crohn's disease (n = 42) displayed significantly higher IgG reactivity to rat GP2 in ELISA than either PAB-negative sera (n = 31), or sera from patients with ulcerative colitis (n = 49), or sera from blood donors (n = 69) (p<0.0001, respectively). Twenty-eight (66%) and 18 (43%) of 42 PAB-positive sera demonstrated IgG and IgA reactivity to human recombinant GP2 in IIF, respectively. Patients with PAB-negative Crohn's disease (n = 31) were not reactive. GP2 mRNA transcription was significantly higher in colon biopsies from patients with Crohn's disease (n = 4) compared to patients with ulcerative colitis (n = 4) (p = 0.0286). Immunochemical staining confirmed GP2 expression in human colon biopsies from patients with Crohn's disease. CONCLUSION: Anti-GP2 autoantibodies constitute novel Crohn's disease-specific markers, the quantification of which could significantly improve the serological diagnosis of IBD. The expression of GP2 in human enterocytes suggests an important role for anti-GP2 response in the pathogenesis of Crohn's disease.

Regulation of in vitro and in vivo immune functions by the cytosolic adaptor protein SKAP-HOM.

SKAP-HOM is a cytosolic adaptor protein representing a specific substrate for the Src family protein tyrosine kinase Fyn. Previously, several groups have provided experimental evidence that SKAP-HOM (most likely in cooperation with the cytosolic adaptor protein ADAP) is involved in regulating leukocyte adhesion. To further assess the physiological role of SKAP-HOM, we investigated the immune system of SKAP-HOM-deficient mice. Our data show that T-cell responses towards a variety of stimuli are unaffected in the absence of SKAP-HOM. Similarly, B-cell receptor (BCR)-mediated total tyrosine phosphorylation and phosphorylation of Erk, p38, and JNK, as well as immunoreceptor-mediated Ca(2+) responses, are normal in SKAP-HOM(-/-) animals. However, despite apparently normal membrane-proximal signaling events, BCR-mediated proliferation is strongly attenuated in the absence of SKAP-HOM(-/-). In addition, adhesion of activated B cells to fibronectin (a ligand for beta1 integrins) as well as to ICAM-1 (a ligand for beta2 integrins) is strongly reduced. In vivo, the loss of SKAP-HOM results in a less severe clinical course of experimental autoimmune encephalomyelitis following immunization of mice with the encephalitogenic peptide of MOG (myelin oligodendrocyte glycoprotein). This is accompanied by strongly reduced serum levels of MOG-specific antibodies and lower MOG-specific T-cell responses. In summary, our data suggest that SKAP-HOM is required for proper activation of the immune system, likely by regulating the cross-talk between immunoreceptors and integrins.

The imbalanced mixed lymphocyte reaction between maternal and fetal lymphocytes as well as between the lymphocytes of adult children and their parents is mediated by activated CD8+ T cells.

PROBLEM: The mixed lymphocyte reaction (MLR) between maternal and fetal lymphocytes as well as between adult children and their parents is imbalanced in bidirectional mixed lymphocyte cultures. The present investigation was aimed at examining which type of T cells has primary responsibility for this phenomenon. METHODS: Two-way mixed lymphocyte cultures between lymphocytes of five female and five male adults and five male and five female newborns against lymphocytes of their parents were performed. Unrelated adults served as the controls. Before and after 72 hr incubation the mixed leukocytes cultures (MLCs) were sorted by flow cytometry according to the surface markers CD4 and CD69 or CD8 and CD69. The single cell populations within the four resulting fractions were discriminated by fluoresence in situ hybridization (FiSH) using xy-DNA probes. RESULTS: Before incubation the share of CD8(+) CD69(+) cells in the MLCs between mothers and their newborn infants was significantly shifted toward the newborn cells (P < 0.01). After 72 hr incubation the CD8(+) CD69(+) ratio in the MLCs between mother and newborn cells and between adult children (male as well female) and their parents showed a significant shift of the CD8(+) CD69(+) cells toward the children's direction. All other MLCs showed a balanced cell population for all investigated cell types, both before and after incubation. CONCLUSION: The imbalanced MLR between maternal and fetal lymphocytes and lymphocytes of adult children against their parents is mediated by a specific imbalance of the activation of CD8(+) but not of CD4(+) T cells.

Arthus reaction to lepirudin, a new recombinant hirudin, and delayed-type hypersensitivity to several heparins and heparinoids, with tolerance to its intravenous administration.

The pathogenesis of allergic reactions to heparin is poorly understood. Clinically, this phenomenon is relevant because of its increasing incidence and the resulting therapeutic challenges due to various cross-reactions between unfractionated and low-molecular weight heparins as well as between heparins and heparinoids. A 44-year-old female patient had developed a delayed-type hypersensitivity to certoparin-sodium. Diagnostic allergy testing revealed various cross-reactions between different heparins as well as an intolerance to heparinoids. After subcutaneous challenge with the recombinant hirudin lepirudin (Refludan) the patient developed a local Arthus reaction at the injection site. In general, recombinant hirudins do not cross-react with high- or low-molecular weight heparins and heparinoids because of a different molecular structure and are therefore an alternative in case of adverse reactions to heparins and heparinoids. Whereas a local Arthus reaction has already been described twice for low-molecular weight heparins, this is to the best of our knowledge the first observation of a superficial leukocytoclastic vasculitis due to s.c. applied lepirudin. Intravenous administration of heparins and heparinoids in case of hypersensitivity to these drugs following topical application risks a generalized eczematous reaction in patients with delayed-type allergy to both groups of substances. In our patient with delayed-type hypersensitivity to heparins and heparinoids and superficial vasculitis due to lepirudin, the intravenous challenge with heparin and a heparinoid was justified as an ultima ratio measure and proved to be the useful therapeutical alternative.

The prevalence and treatment of headache sufficient to impact on the quality of life of undergraduate students entering university.

AIM OF STUDY: Headache has a significant impact on public health in terms of quality of life and economic consequences, but in primary care, needs often remain unmet in terms of recognition, diagnosis and treatment. Our aim was to measure the prevalence of headache sufficient to affect the quality of life of undergraduate students who were entering the University of Exeter. METHOD: 1124 consecutive undergraduate entrants aged 21 and under who registered at the Student Health Centre at the beginning of the academic year were invited to complete a questionnaire during their registration procedure. We used the Headache Impact Score to measure effect of headache on quality of life. RESULTS: A completed questionnaire was received from 1057 (94%) students registering at the Health Centre. 212 (21%) of these students had headaches that affected the quality of their life. Of these, 95 (45%) had seen a doctor previously about their headaches and 28 (13%) had headaches on more than 15 days a month. Less than 5% were taking prescription medication. The headache impact score was 56 indicating a substantial impact on quality of life of students. CONCLUSION: Headache has a considerable impact on the quality of life of students entering University which we speculate may have a deleterious effect on educational attainment. This study has confirmed the findings of other population groups that morbidity from headache is often unrecognised and under treated.

Targeting dipeptidyl peptidase IV (CD26) suppresses autoimmune encephalomyelitis and up-regulates TGF-beta 1 secretion in vivo.

CD26 or dipeptidyl peptidase IV (DP IV) is expressed on various cell types, including T cells. Although T cells can receive activating signals via CD26, the physiological role of CD26/DP IV is largely unknown. We used the reversible DP IV inhibitor Lys[Z(NO(2))]-pyrrolidide (I40) to dissect the role of DP IV in experimental autoimmune encephalomyelitis (EAE) and to explore the therapeutic potential of DP IV inhibition for autoimmunity. I40 administration in vivo decreased and delayed clinical and neuropathological signs of adoptive transfer EAE. I40 blocked DP IV activity in vivo and increased the secretion of the immunosuppressive cytokine TGF-beta1 in spinal cord tissue and plasma during acute EAE. In vitro, while suppressing autoreactive T cell proliferation and TNF-alpha production, I40 consistently up-regulated TGF-beta1 secretion. A neutralizing anti-TGF-beta1 Ab blocked the inhibitory effect of I40 on T cell proliferation to myelin Ag. DP IV inhibition in vivo was not generally immunosuppressive, neither eliminating encephalitogenic T cells nor inhibiting T cell priming. These data suggest that DP IV inhibition represents a novel and specific therapeutic approach protecting from autoimmune disease by a mechanism that includes an active TGF-beta1-mediated antiinflammatory effect at the site of pathology.

A cost consequence study of the impact of a dermatology-trained practice nurse on the quality of life of primary care patients with eczema and psoriasis.

BACKGROUND: The practice nurse is central to the development of a primary care-led National Health Service. Skin diseases can have a major impact on patients' lives but general practitioners (GPs) lack many of the skills of practical dermatology care and support. AIM: To determine whether a primary care dermatology liaison nurse should be introduced by our health authority. We identified the resources consumed and the benefits that accrued from a practice nurse who had received training in practical dermatology care. METHOD: A cost consequence study in parallel with a randomised controlled trial was undertaken in a group of nine GPs and 109 patients between the ages of 18 and 65 years who had a diagnosis of psoriasis or eczema. RESULTS: Although there was a significant improvement in our primary outcome measure within group, when compared with the control group significance was not achieved. There was no significant change in the Euroqol measure but the clinical instrument showed a significant change when compared with control. On entry, our qualitative data identified three main themes--the embarrassment caused by these skin conditions, the wish for a cure rather than treatment, and concern over the long-term effects of steroids. On completion, 20% of patients expressed that they had received a positive benefit from the clinic. CONCLUSION: This study demonstrates the difficulties of obtaining relevant information to facilitate decisions on how resources should be allocated in primary care. Not all questions can be answered by large multi-centred trials and studies themselves have an opportunity cost consuming resources that could otherwise be spent on direct health care. Often, local resource decisions will be based on partial evidence-yielding solutions that are satisfactory rather than optimum but which are, nevertheless, better than decisions taken with no evidence at all.

Down-regulation of T cell activation following inhibition of dipeptidyl peptidase IV/CD26 by the N-terminal part of the thromboxane A2 receptor.

Using synthetic inhibitors, it has been shown that the ectopeptidase dipeptidyl peptidase IV (DP IV) (CD26) plays an important role in the activation and proliferation of T lymphocytes. The human immunodeficiency virus-1 Tat protein, as well as the N-terminal nonapeptide Tat(1-9) and other peptides containing the N-terminal sequence XXP, also inhibit DP IV and therefore T cell activation. Studying the effect of amino acid exchanges in the N-terminal three positions of the Tat(1-9) sequence, we found that tryptophan in position 2 strongly improves DP IV inhibition. NMR spectroscopy and molecular modeling show that the effect of Trp(2)-Tat(1-9) could not be explained by significant alterations in the backbone structure and suggest that tryptophan enters favorable interactions with DP IV. Data base searches revealed the thromboxane A2 receptor (TXA2-R) as a membrane protein extracellularly exposing N-terminal MWP. TXA2-R is expressed within the immune system on antigen-presenting cells, namely monocytes. The N-terminal nonapeptide of TXA2-R, TXA2-R(1-9), inhibits DP IV and DNA synthesis and IL-2 production of tetanus toxoid-stimulated peripheral blood mononuclear cells. Moreover, TXA2-R(1-9) induces the production of the immunosuppressive cytokine transforming growth factor-beta1. These data suggest that the N-terminal part of TXA2-R is an endogenous inhibitory ligand of DP IV and may modulate T cell activation via DP IV/CD26 inhibition.

What does it cost the patient to see the doctor?

Against a background of increasing demands on limited resources, there will be an emphasis on undertaking studies that relate benefits of an intervention to the costs that are incurred in their production. Patient costs are an important, but often overlooked, part of an economic exercise and include transport costs, loss of employment, and loss of leisure time. This paper highlights the theoretical difficulties inherent in deriving patient costs and suggests a pragmatic framework to derive unit costs in these areas. We demonstrate that these costs are not inconsiderable when compared with the cost of a general practitioner consultation.