Immunologic Sensitization Research Articles

Association of device surface and biomaterials with immunologic sensitization after mechanical support

Biomaterials and textured surfaces in early pulsatile left ventricular assist devices (HeartMate I; Thoratec Corporation, Pleasanton, Calif) may increase immunologic risk through allosensitization. We hypothesized that axial-flow devices without biologic membranes or textured surfaces (HeartMate II; Thoratec; and DeBakey; MicroMed Cardiovascular, Inc, Houston, Tex) would cause less allosensitization than devices with such membranes and surfaces. HeartMate II and DeBakey (n = 24) and HeartMate I (n = 36) devices were implanted from 1999 to 2006 in patients with severe heart failure cohort-matched for age, etiology, and support duration. Serum samples reacting with more than 10% of the HLA reference panel were considered positive for anti-HLA antibodies. Endomyocardial biopsy samples were collected after transplant. There were no significant cohort differences in age, etiology, sex, blood transfusion, or support duration. Anti-HLA antibodies were not detected at implantation of either HeartMate II and DeBakey or HeartMate I devices; however, significant increases in anti-HLA antibodies were present within 1 and 3 months of support with HeartMate I but not HeartMate II and DeBakey devices. Overall, fewer patients with HeartMate II and DeBakey devices demonstrated positive anti-HLA antibodies during support (8% vs 28%, P = .02), and fewer episodes of acute rejection per patient were seen within the first 9 posttransplant months(0.31 vs 0.69, P = .052). Long-term posttransplant survival was not different between groups. Hemodynamic support with HeartMate II and DeBakey devices produced less allosensitization than did HeartMate I devices. Device selection may improve clinical outcomes for high-risk patients.

313: HLA-Sensitization in Infants after Repair of Hypoplastic Left Heart Syndrome (HLHS) Is Prevented by Use of Glutaraldehyde-Treated Homografts

Cryopreserved allograft tissue (‘homografts’) used in the Norwood procedure for infants with HLHS causes a marked immunologic sensitization which may complicate future heart transplantation. Treatment of the allograft patch prior to implantation may prevent this sensitization. The purpose of this study was to assess the anti-human leukocyte antigen (HLA) antibody response to glutaraldehyde-treated allograft patches used in the repair of HLHS.

Chronic Allograft Nephropathy

Chronic allograft nephropathy (CAN) remains the Achilles heel of renal transplantation. In spite of the significant strides achieved in one-year renal allograft survival with newer immunosuppressant strategies, the fate of long-term renal allograft survival remains unchanged. The number of renal transplant recipients returning to dialysis has doubled in the past decade. This is especially important since these patients pose a significantly increased likelihood of dying while on the waiting list for retransplantation, due to increasing disparity between donor organ availability versus demand and longer waiting time secondary to heightened immunologic sensitization from their prior transplants. In this review we analyze the latest literature in detail and discuss the definition, natural history, pathophysiology, alloantigen dependent and independent factors that play a crucial role in CAN and the potential newer therapeutic targets on the horizon. This article highlights the importance of early identification and careful management of all the potential contributing factors with particular emphasis on prevention rather than cure of CAN as the core management strategy.

The primary clinical trial of dendritic cell vaccine pulsed with apoptosis tumor cell in patients with malignant cancers

13509 Background: We evaluated the feasibility, safety, and immunogenicity of mature, apoptosis tumor cells-pulsed dendritic cell (DC) vaccines administered by intradermal injection. Methods: We performed a randomized study in 16 patients with malignant tumors, including 4 cases for gastric cancer, 3 cases for prostate cancer, 2 cases for breast cancers, one case for lung cancer, esophageal carcinoma, liver cancer , colorectal cancer, kidney cancer, ovarian cancer, endometrial cancer respectively.The vaccine used mature DCs (CD11c++, HLA-DR++, CD83+, and CD86+++) generated from peripheral blood monocytes in the presence of GM-CSF and IL-4. After 5 days, DCs were matured with a defined cocktail of cytokines (IL-1+ TNF-a+PGE2) and simultaneously pulsed with apoptosis autologous tumor cells or heterologous tumor cell lines, for 2 days.Patients were administrated four DC vaccinations (5×106 per time) at 7th day, 14th day, 21st day and 42nd day by intradermal injection(ID). Toxicity effect, life quality, immune function and clinical efficacy were monitored during the whole therapy. Results: Fourteen (82.4%) of 17 patients completed all four vaccinations. Vaccinations were well tolerated; a few patients exhibited less than grade 1 toxicities including rash, transient fever, transient debilitation and injection site reaction. The life quality of most patients had improved to certain degree, including sleep, appetite, mental status, and a good recovery from surgery and chemotherapy. Moreover, the serum level of IL-2 of 10/14 patients increased more than several times to twenty times, and 6/10 patients had a long increase for more than forty days. Serum level of IL-12 were increase in 11/14(9/11 patients increased for more than forty days) patients, Serum level of IFN-? were increase in 11/14(5/11 patients increased for more than forty days ) patients. Conclusions: Administration of this apoptosis tumor cell-pulsed mature DC vaccine by ID routes is feasible and safe. This administration seems to result in superior immunological sensitization as measured by in vitro serum level of immune cell factor such as IL-2, IL-12 and IFN-?. No significant financial relationships to disclose.

The effect of skin allografting on the equine endometrial cup reaction

This research tested the hypothesis that immunological sensitization of mares by skin allografting, followed by the establishment of pregnancy using semen from the skin-graft donor, would give rise to secondary immune responses to the developing horse conceptus, resulting in an earlier demise of the fetally derived endometrial cups. Maiden mares received skin allografts from a stallion homozygous for Major Histocompatibility Complex (MHC) antigens and/or equivalent autografts and were subsequently mated to the skin-graft donor stallion during the next two breeding seasons. Mares that had been immunologically primed to the foreign MHC class I antigens of the skin-graft donor stallion developed strong secondary antibody responses early in their first pregnancies, whereas autografted mares made weak primary antibody responses in their first pregnancies and strong secondary responses in their second pregnancies. In contrast, histological examination of the endometrial cups after surgical pregnancy termination at Day 60 of gestation revealed no discernible differences between allografted and autografted mares, and there were no significant differences in the concentrations and/or duration of secretion of the endometrial cup-specific hormone, equine chorionic gonadotrophin (eCG), between allografted and autografted mares, nor in either group between first and second pregnancies. The vigorous antibody response observed in the pregnant allografted mares supported the first part of our hypothesis, providing evidence of systemic immunological priming. However, there was a lack of an equivalent heightened cellular response to the endometrial cups. These findings provided strong evidence for an asymmetric immune response to the conceptus, characterized by strong humoral immunity and a dampened cellular response.

Effect of high-pressure treatment on in-vitro digestibility of β-lactoglobulin

The effect of high-pressure (HP)-treatment on β-lactoglobulin (β-Lg) was investigated using in-vitro pepsin digestion under simulated gastric conditions. HP-treatment of β-Lg at 400 MPa for 10 min only slightly increased its subsequent hydrolysis by pepsin. However, higher pressure treatments (600 and 800 MPa) resulted in rapid digestion of β-Lg. After these higher pressure treatments, β-Lg disappeared in less than 1 min of pepsin incubation as determined by SDS-PAGE analysis. Mass spectrometry analysis of the digestion products at corresponding incubation times revealed rapid and progressive degradation of β-Lg. Most (> 90%) of the peptide products following pepsin digestion of HP-treated β-Lg were less than 1500 Da in size. Peptide products from pepsin digestion were identified and mapped to β-strand regions (Leu32–Leu54 and Phe82–Leu104) and to the N- and C-terminals regions (Leu1–Leu10 and Ser150–Leu156) of β-Lg. While these regions corresponded to known IgE epitopes of β-Lg, the predominant peptides resulting from 60 s of incubation were short (7–10 residues) in length. These results demonstrate that HP-treatment increased the digestibility of β-Lg and represents a promising processing technology for reducing the allergenicity of known allergens in a wide variety of food materials. High-pressure treatment is widely used to enhance the functional attributes of food proteins. The potential for enhanced nutritional value of β-Lg was also demonstrated here by its increased digestibility. High-pressure treatment followed by incubation with proteases may represent a method for the commercial production of bioactive peptides such as inhibitors of angiotensin converting enzyme. More importantly, high-pressure-induced unfolding of milk proteins may reduce their allergenicity. Unfolded proteins are less likely to become agents of immunological sensitization because they are more readily hydrolyzed. Thus high-pressure treatment applied to food ingredients such as whey protein isolate may contribute to the development of hypoallergenic foods.

Failure of prophylactic intravenous immunoglobulin to prevent sensitization to cryopreserved allograft tissue used in congenital cardiac surgery

Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome causes profound immunologic sensitization, which may complicate future transplantation. Intravenous immunoglobulin has been shown to reduce sensitization after it has developed, allowing successful transplantation. The purpose of this pilot trial was to determine whether intravenous immunoglobulin given before and after the procedure could prevent sensitization to cryopreserved allograft patches used in the initial repair of hypoplastic left heart syndrome. Intravenous immunoglobulin (2 g/kg) was given preoperatively, 3 weeks postoperatively, and 4 months postoperatively to 7 infants undergoing the Norwood procedure. Panel-reactive antibodies were measured with flow cytometry preoperatively and at 1, 4, 6, and 12 months postoperatively and compared with values from a contemporary cohort of 12 infants undergoing the Norwood procedure who did not receive intravenous immunoglobulin. The groups were well matched for length and weight at time of surgery. Control infants were somewhat younger than the cohort receiving intravenous immunoglobulin (8 +/- 5 vs 17 +/- 14 days, P = .021). There were no differences in transfusion requirements. There was no difference in the degree of sensitization between control and intravenous immunoglobulin groups at 1 month (class I panel-reactive antibodies 20% +/- 30% vs 4% +/- 9%, P = .443, class II panel-reactive antibodies 17% +/- 27% vs 20% +/- 17%, P = .400), 4 months (class I panel-reactive antibodies 62% +/- 40% vs 73% +/- 41%, P = .813, class II panel-reactive antibodies 49% +/- 42% vs 54% +/- 41%, P = .706), and 12 months (class I panel-reactive antibodies 49% +/- 42% vs 58% +/- 39%, P = .686, class II panel-reactive antibodies 44% +/- 36% vs 49% +/- 42%, P = .651). Despite studies showing intravenous immunoglobulin to reduce sensitization, we were unable to demonstrate that intravenous immunoglobulin prevented sensitization after exposure to allograft tissue in neonates undergoing congenital cardiac surgery.

Understanding the Sensitized Patient

New technologies have resulted in the ability to identify the presence of IgG human leukocyte antigen (HLA) or non-HLA antibodies in the sera of potential solid organ transplant recipients. Knowledge of the presence of these antibodies, their antigen specificities, and strength (titer) is crucial to understanding a patient's state of immunologic sensitization and reactivity. Finally, these data, when correlated with sensitive crossmatch results, allow clinicians to make more knowledgeable clinical decisions when paring donors and recipients for transplant.

Defining and investigating occupational asthma: a consensus approach

Background: At present there is no internationally agreed definition of occupational asthma and there is a lack of guidance regarding the resources that should be readily available to physicians running...

Preoperative single-bolus high-dose antithymocyte globulin as induction therapy in sensitized renal transplant recipients

Immunological sensitization remains a major problem following renal transplantation. There is no consensus for the management of sensitized renal allograft recipients. The patients become tethered to dialysis while waiting for compatible donors. This study was designed to evaluate the efficacy and safety of preoperative single-bolus high-dose antithymocyte globulin (ATG) as induction therapy in sensitized renal transplant recipients. A total of 56 patients were divided into two groups according to the level of panel reactive antibody (PRA): non-sensitized group (PRA < 10%, n = 30) and sensitized group (PRA > or = 10%, n = 26). The characteristics of the recipients and donors were comparable between the two groups. Mycophenolate mofetil (MMF, 1 g) or ATG (iv. 9 mg/kg) were given preoperatively in the two groups as induction therapy. After the transplantation, the patients were treated with standard triple therapy regimen consisting of tacrolimus (FK-506) or cyclosporine A, MMF, and prednisolone. Acute rejection (AR) and infection episodes were recorded and renal function was monitored during a 12-month follow-up. Chi(2) test and t test were used to analyze the data. During the follow-up, 6 patients (20.0%) suffered AR episodes in the non-sensitized group and 4 (15.4%) in the sensitized group (P = 0.737); 8 patients (26.7%) experienced 11 infection episodes (average, 1.4 episodes per infected patient) in the non-sensitized group, and 6 (23.1%) experienced 10 infection episodes (average, 1.7 episodes per infected patient) in the sensitized group (P = 0.757, 0.890). The safety of the drugs, which was assessed by the occurrence of side effects, was comparable between the two groups. The hospital stay was 13 - 25 days (mean, 16.7 +/- 3.3) in the non-sensitized group and 14 - 29 days (mean, 16.2 +/- 3.1) in the sensitized group, respectively (P = 0.563). No delayed graft function (DGF) was observed in all the patients. Both the 12-month actuarial patient and graft survival rates were 100% in the two groups. Preoperative single-bolus high-dose ATG is an effective and safe induction therapy yielding acceptable acute rejection rate in sensitized renal transplant recipients.

Lung surfactants

The pharmacology, clinical efficacy, and cost considerations of exogenous lung surfactants are reviewed. Exogenous pulmonary surfactants, along with advancements in ventilatory care, have significantly reduced the incidence of respiratory distress syndrome (RDS) and its related complications in infants. The following exogenous surfactants are approved for the prophylaxis and treatment (rescue) of neonatal RDS: beractant, a modified natural surfactant; calfactant and poractant, both natural surfactants; and colfosceril, a synthetic surfactant that is not currently available in the United States. Lucinactant, a synthetic surfactant, is under investigation and received approvable status from the Food and Drug Administration in February 2005. The surfactants are delivered directly to their site of action, and only small amounts reach the systemic circulation. Bioavailability to the distal airways and alveoli depends on the method of delivery, the stage and severity of pulmonary disease, and the properties of the particular surfactant. According to data from clinical trials, the use of exogenous surfactant therapy for rescue within the first two hours of life appears to be as efficacious as prophylaxis in most premature infants. Comparative trials of surfactants have proven the efficacy of both synthetic and natural surfactants in the prevention and treatment of RDS. However, these trials have universally demonstrated greater reduction in the immediate need for ventilator support in infants who receive natural surfactants. Natural preparations cause less pneumothorax, bronchopulmonary dysplasia, and mortality compared with synthetic preparations. Synthetic agents offer the potential advantages of an unlimited supply with consistent pharmaceutical quality and no risk of transmitting infectious disease or causing immunologic sensitization.

Mice lacking the VIP gene show airway hyperresponsiveness and airway inflammation, partially reversible by VIP

The mechanisms leading to asthma, and those guarding against it, are yet to be fully defined. The neuropeptide VIP is a cotransmitter, together with nitric oxide (NO), of airway relaxation, and a modulator of immune and inflammatory responses. NO-storing molecules in the lung were recently shown to modulate airway reactivity and were proposed to have a protective role against the disease. We report here that mice with targeted deletion of the VIP gene spontaneously exhibit airway hyperresponsiveness to the cholinergic agonist methacholine as well as peribronchiolar and perivascular cellular infiltrates and increased levels of inflammatory cytokines in bronchoalveolar lavage fluid. Immunologic sensitization and challenge with ovalbumin generally enhanced the airway hyperresponsiveness and airway inflammation in all mice. Intraperitoneal administration of VIP over a 2-wk period in knockout mice virtually eliminated the airway hyperresponsiveness and reduced the airway inflammation in previously sensitized and challenged mice. The findings suggest that 1) VIP may be an important component of endogenous anti-asthma mechanisms, 2) deficiency of the VIP gene may predispose to asthma pathogenesis, and 3) treatment with VIP or a suitable agonist may offer potentially effective replacement therapy for this disease.

Occupational rhinitis

This review updates existing knowledge on occupational rhinitis based on epidemiological and clinical research studies published from 2003 to 2005. The review covers new developments on the pathophysiology, diagnosis, monitoring and management of occupational rhinitis. This article also provides updated information on the prevalence and incidence of both occupational rhinitis and work-related symptoms of rhinitis, as well as on causal agents and personal risk factors associated with this condition. Occupational rhinitis is frequently under-diagnosed due to a lack of physician awareness. Diagnosis is suspected when symptoms occur in relation to work. Differentiating between immunological sensitization and irritation may be difficult. Given the high prevalence of rhinitis in the general population from all causes, objective tests confirming the occupational origin are essential. Measures of inflammatory parameters via nasal lavage and objective assessment of nasal congestion both offer practical means of monitoring responses. Growing experience with acoustic rhinometry and peak nasal inspiratory flow suggests that these methods will have an increasingly important role in monitoring and diagnosing in the future. Recent findings indicate that work-related rhinitis is to some extent preventable. Surveillance of sensitized workers may allow early detection of occupational rhinitis.

Allogeneic bone marrow stromal cells promote glial–axonal remodeling without immunologic sensitization after stroke in rats

We evaluated the effects of allogeneic bone marrow stromal cell treatment of stroke on functional outcome, glial–axonal architecture, and immune reaction. Female Wistar rats were subjected to 2 h of middle cerebral artery occlusion. Rats were injected intravenously with PBS, male allogeneic ACI – or syngeneic Wistar –bone marrow stromal cells at 24 h after ischemia and sacrificed at 28 days. Significant functional recovery was found in both cell-treated groups compared to stroke rats that did not receive BMSCs, but no difference was detected between allogeneic and syngeneic cell-treated rats. No evidence of T cell priming or humoral antibody production to marrow stromal cells was found in recipient rats after treatment with allogeneic cells. Similar numbers of Y-chromosome + cells were detected in the female rat brains in both groups. Significantly increased thickness of individual axons and myelin, and areas of the corpus callosum and the numbers of white matter bundles in the striatum were detected in the ischemic boundary zone of cell-treated rats compared to stroked rats. The areas of the contralateral corpus callosum significantly increased after cell treatment compared to normal rats. Processes of astrocytes remodeled from hypertrophic star-like to tadpole-like shape and oriented parallel to the ischemic regions after cell treatment. Axonal projections emanating from individual parenchymal neurons exhibited an overall orientation parallel to elongated radial processes of reactive astrocytes of the cell-treated rats. Allogeneic and syngeneic bone marrow stromal cell treatment after stroke in rats improved neurological recovery and enhanced reactive oligodendrocyte and astrocyte related axonal remodeling with no indication of immunologic sensitization in adult rat brain.

Decellularization reduces the immune response to aortic valve allografts in the rat

Cryopreserved valve allografts used in congenital cardiac surgery are associated with a significant cellular and humoral immune response. This might be reduced by removal of antigenic cellular elements (decellularization). The aim of this study was to determine the immunologic effect of decellularization in a rat allograft valve model. Brown Norway and Lewis rat aortic valves were decellularized with a series of hypotonic and hypertonic buffers, protease inhibitors, gentle detergents (Triton X-100), and phosphate-buffered saline. Valves were implanted into Lewis rats in syngeneic and allogeneic combinations. Cellular (CD3 and CD8) infiltrates were assessed with morphometric analysis, and the humoral response was assessed with flow cytometry. Morphometric analysis identified a significant reduction in CD3 + cell infiltrates (cells per square millimeter of leaflet tissue) in decellularized allografts compared with that seen in nondecellularized allografts at 1 (79 +/- 29 vs 3310 +/- 223, P < .001), 2 (26 +/- 11 vs 109 +/- 20, P = .004), and 4 weeks (283 +/- 122 vs 984 +/- 145, P < .001). Anti-CD8 staining confirmed the majority of infiltrates were cytotoxic T cells. Flow cytometric mean channel fluorescence intensity identified a negative shift (abrogated antibody formation) for decellularized allografts compared with nondecellularized allografts at 2 (19 +/- 1 vs 27 +/- 3, P = .033), 4 (35 +/- 2 vs 133 +/- 29, P = .001), and 16 weeks (28 +/- 2 vs 166 +/- 54, P = .017). Decellularization significantly reduces the cellular and humoral immune response to allograft tissue. This could prolong the durability of valve allografts and might prevent immunologic sensitization of allograft recipients.

Immunogenetic factors in beryllium sensitization and chronic beryllium disease

Exposure to beryllium in the workplace can cause beryllium sensitization and chronic beryllium disease. Sensitization to beryllium can be detected in the laboratory using the beryllium lymphocyte proliferation test. It was shown that anti-HLA antibodies could block the beryllium-specific response in the beryllium lymphocyte proliferation test, thereby implicating HLA genes in chronic beryllium disease. A supratypic genetic marker, HLA-DPB1*E69, was found to be strongly associated with immunologic sensitization to beryllium and chronic beryllium disease in beryllium workers. However, there are 40 HLA-DPB1 gene variants that have E69 but that also have other DNA sequence variations. The purpose of the study was to evaluate the evidence for potential differential susceptibility that may be associated with the physical characteristics of HLA protein molecules for which different HLA-DPB1*E69 variants code; that is, do some HLA-DPB1*E69 variants convey higher risk of beryllium sensitization and chronic beryllium disease than others. To do this, two approaches were pursued: first, detailed analysis of the findings from the published literature was performed, and second, computational chemistry was used to seek clues concerning the physical properties of the HLA protein molecules for which these alleles code. Among the 40 HLA-DPB1 gene variants that code for E69, molecular epidemiological studies have suggested a risk hierarchy, where some variants appear to convey low to moderate risk of chronic beryllium disease (e.g., HLA-DPB1*0201, ∼3-fold increased risk), some convey an intermediate risk (e.g., HLA-DPB1*1901, ∼5-fold) and others convey high risk (e.g., HLA-DPB1*1701, >10-fold). Molecular modeling has been used to further investigate a potential mechanistic basis for these observations. We found a strong correlation between the hierarchical order of risk of chronic beryllium disease associated with specific alleles and the predicted surface electrostatic potential and charge of the corresponding isotypes. Therefore, when alleles were grouped by the relative negative charge on the molecules for which they code, the data suggest that those alleles associated with the most negatively charged proteins carry the greatest risk of beryllium sensitization and disease.

The use of concentrated bovine serum albumin in canines

In humans it has been estimated that for each 2.5 g L–1 decrease in serum albumin, risk of death increases by 24–56%. Clinical impression suggests this may be similar in veterinary patients. Species-specific albumin (plasma) is often unavailable and concentrated solutions are not. Our experience using 25% human serum albumin (HSA) in critically ill dogs suggests a positive effect (results submitted), however it is expensive. Bovine serum albumin (BSA) may be a more cost effective and readily available alternative. The purpose of this study was to assess the immediate and long-term safety of an intravenous dose (500 mg kg–1) of bovine albumin administered to healthy dogs. Ten mature dogs (eight males, two females, 28 ± 6 kg) were to receive BSA (250 mg mL–1) twice (BSA1 and BSA2) with 14 days between treatments. Temperature, blood pressure, and pulse and respiration rate were continuously monitored to identify a reaction to BSA. All dogs received BSA1. One dog immediately developed mild urticaria and pruritus, otherwise the infusion was well tolerated. No immediate reaction was noted in the other nine dogs. Two dogs received BSA2. One dog developed a mild immediate reaction similar to that occurring with BSA1, and one dog (the dog immediately reacting to BSA1) developed a severe anaphylactic reaction. Due to these reactions, no other dogs received BSA2. During a two-week observation of the remaining eight dogs given BSA1, five developed a mild or severe generalized type-III hypersensitivity reaction. The dog experiencing a mild reaction during BSA2 administration also developed a generalized type-III hypersensitivity reaction. Delayed reactions occurred 15 ± 2.7 days after BSA exposure. Three dogs did not develop a reaction. All reacting dogs recovered fully. The severity of reactions, and the number of dogs affected, suggests prior (natural) exposure and immunological sensitization to bovine albumin. Bovine serum albumin is not suitable for therapeutic use in dogs.

Food hypersensitivity—immunologic (peripheral) or cognitive (central) sensitisation?

Patients with food hypersensitivity suffer poor quality of life and several unexplained health complaints, both abdominal and extra-abdominal. Part of the suffering is due to healthcare providers' neglect and poor insight, allowing a strong position for alternative medicine. Distinguishing food allergy from functional and organic disorders can be extremely difficult. We have found examination of faecal calprotectin and gut permeability to be useful for excluding organic disease, whilst conventional provocation tests for positive diagnosis of food hypersensitivity are cumbersome. Our new ultrasound provocation test has been promising, but we acknowledge that much work remains to be done before its sensitivity and specificity can be finally established. The majority of patients with self-reported food hypersensitivity have a non-allergic hypersensitivity disorder. We suggest that cognitive-emotional sensitisation at the brain level, and not peripheral (immunological) sensitisation, is a major pathogenetic mechanism by which the patients' various abdominal and extra-abdominal health complaints are generated. Extensive activation of cognitive networks might be triggered by peripheral sensory mechanisms, often misinterpreted as 'food allergy'. Clearly, the approach to patients with food hypersensitivity should be interdisciplinary.

Course of contact allergy in consecutive eczema patients patch tested with TRUE Test™ panels 1 and 2 at least twice over a 12‐year period

Non-reproducibility of positive patch test reactions is common. In this retrospective study, we investigated the reproducibility of previously positive patch test reactions and the appearance of new positive reactions in a consecutive series of 264 eczema patients tested at least twice over a 12-year period using the TRUE Test standardized patch test system. Out of 297 positive reactions, 66% remained positive in a 2nd test, 10% were scored as doubtful and 24% as negative. Among the previously recorded doubtful reactions, 13% were positive in the 2nd test, 13% were again doubtful and 74% negative. In relation to the degree of patch test reactivity, 48% of the + reactions were reproducible, compared to 87% of ++ and +++ reactions. No difference in reproducibility was observed between patients tested with a short or a long-time interval between tests. With the use of the TRUE Test panels 1 and 2, methodological factors are minimized. The variation in patch test positivity may then be attributed to biological variation, which depends on several individual factors such as patch test reading, patient-related factors such as changed immunological sensitivity, regional variation of the skin on the back and the presence of more or less active dermatitis.

Use of an allograft patch in repair of hypoplastic left heart syndrome may complicate future transplantation

Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome (HLHS) has the potential to cause marked immunologic sensitization which may complicate potential future heart transplantation, if required. The purpose of this study was to assess the anti-HLA antibody response to allograft patches used in the initial repair of HLHS. A prospective cohort study was conducted comparing the panel-reactive antibody levels (PRA) in 12 infants undergoing repair of HLHS with cryopreserved allograft patch to 10 infants undergoing arterial switch for transposition of the great arteries (no allograft tissue used). PRA for Class I (HLA-A, B, C) and Class II (HLA-DR, DQ) antibodies were assessed preoperatively and postoperatively using flow cytometry. The two groups were well matched at the time of surgery (age, weight, gender). Infants in both groups received blood from multiple donors; however, the allograft group received significantly more (12+/-10 vs. 5+/-1 units; P<0.001). By 4 months, most infants receiving allograft tissue had become highly sensitized for both Class I PRA (62+/-40 vs. 0; P=0.002) and Class II PRA (49+/-42 vs. 2+/-3; P=0.022). This response continued to increase at 12 months: Class I PRA (79+/-21 vs. 0; P=0.008) and Class II PRA (66+/-27 vs. 5+/-6; P=0.008). Specificity analysis confirmed antibodies were specific for the donor allograft HLA type. In addition, infants who were coincidently HLA-matched with their allograft did not develop an elevated PRA. Allograft tissue used in the repair of HLHS is associated with profound donor specific immunologic sensitization in the majority of recipients and may complicate or jeopardize future transplantation. Methods to reduce the immunogenicity of cryopreserved allograft tissue used for arch reconstruction requires further investigation.