British Society for Immunology/United Kingdom Primary Immunodeficiency Network consensus statement on managing non-infectious complications of common variable immunodeficiency disorders

Common variable immunodeficiency (CVID) represents a heterogeneous group of rare disorders. There is considerable morbidity and mortality as a result of non-infectious complications, and this presents clinicians with management challenges. Clinical guidelines to support the management of CVID are urgently required. The UK Primary Immunodeficiency Network and the British Society for Immunology funded a joint project to address this. A modified Delphi Survey was conducted for the assessment, diagnosis and treatment of the non-infectious blood, respiratory, gut and liver complications of CVID. A steering group of 10 consultant immunologists and one nurse specialist developed and reviewed the survey statements and agreed the final recommendations. In total, 22 recommendations and three areas for research were developed.

UK NEQAS survey of allergen component testing across the United Kingdom and other European countries

The clinical utility of molecular diagnostic approaches in allergy investigation is being recognized increasingly to play a significant role in the management of allergic patients. Determining the sensitization pattern, which is best achieved through the use of component resolved diagnostics (CRD), allows effective risk stratification, appropriate treatment and patient selection for immunotherapy. In order to assess the diagnostic service provisions for in-vitro allergy testing across Europe, a survey was carried out via the total immunoglobulin (Ig)E and specific IgE external quality assurance schemes run by UK National External Quality Assessment Service (NEQAS) Immunology, Immunochemistry and Allergy. This survey assessed allergy testing, and in particular allergen components offered by the laboratories, and found a wide variability in service provision, particularly between the United Kingdom and other European Union (EU) countries. Furthermore, there was lack of standardization for acquisition of clinical information to aid allergen (and component) selection, gating strategy, testing algorithms and clinical interpretation. Interestingly, a significant proportion of laboratories (the majority from EU) stated that they 'used' the results for peanut components for risk stratification. However, the vast majority of participants were unaware of guidelines relating to the use of allergen component testing, and agreed that further education would assist in reaching a common platform. Hence, this survey has highlighted that although CRD has been adopted into routine diagnostics across Europe, it is potentially compromised by lack of standardized protocols and guidance sources. Consequently, there is a need for local or national standards and education through External Quality Assurance services on the performance and application of CRD into allergy investigation.

Chlorhexidine allergy in four specialist allergy centres in the United Kingdom, 2009-13: clinical features and diagnostic tests

We describe an observational survey of diagnostic pathways in 104 patients attending four specialist allergy clinics in the United Kingdom following perioperative hypersensitivity reactions to chlorhexidine reactions. The majority were life-threatening. Men undergoing urological or cardiothoracic surgery predominated. Skin prick testing and specific immunoglobulin (sIg)E testing were the most common tests used for diagnosis. Fifty-three per cent of diagnoses were made on the basis of a single positive test. Where multiple tests were performed the sensitivity of intradermal, basophil activation and skin prick testing was 68% (50-86%), 50% (10-90%) and 35% (17-55%), respectively. Seven per cent were negative on screening tests initially, and 12 cases were only positive for a single test despite multiple testing. Intradermal tests appeared most sensitive in this context. Additional sensitization to other substances used perioperatively, particularly neuromuscular blocking agents (NMBA), was found in 28 patients, emphasizing the need to test for possible allergy to all drugs to which the patient was exposed even where chlorhexidine is positive.

Falsely low immunoglobulin (Ig)G4 in routine analysis: how not to miss IgG4 disease

Immunoglobulin (Ig)G4 disease can have apparently 'normal' levels of IgG4 due to antigen excess conditions. IgG4 measurement therefore appears falsely low. UK National External Quality Assurance Scheme (UK NEQAS) data and other reports have suggested that this problem occurred despite pre-existing antigen excess detection steps. To determine the clinical relevance of the problem, we examined the prevalence and characteristics of prozoning in our laboratory and patient cohorts. We establish that the prevalence of raised IgG4 in routine IgG4 analysis is low (< 1%) using one of the two routine methods in use in the United Kingdom. We show that subsequent assay modification appears to have reduced the likelihood of misleading readings. However, the original version of the assay prozoned to low levels (below 0·64 g/l) in 41% of high IgG4 samples in our patients. This may explain the previous reports of low sensitivity of raised IgG4 for IgG4RD, and predictive values should be re-evaluated in this disease using modified prozone-resistant protocols. All laboratories providing IgG4 measurements should verify that their assays are fit for the clinical quality requirement of detection raised IgG4 levels and must verify the upper limit of their reference ranges and freedom from prozoning.

High-titre circulating tissue transglutaminase-2 antibodies predict small bowel villous atrophy, but decision cut-off limits must be locally validated

Numerous studies suggest that high levels of circulating immunoglobulin (Ig)A tissue transglutaminase (TTG2) antibodies predict coeliac disease with high specificity. Accordingly, it has been suggested that duodenal biopsy may not be required routinely for diagnostic confirmation where quantitative serology identifies the presence of high antibody titres. However, defining a cut-off TTG2 threshold is problematic, as the multiple available assay methods are not harmonized and most studies have been focused on the paediatric population. Recent paediatric guidelines proposed a TTG2 antibody diagnostic cut-off at 10 × the upper limit of normal (ULN) for the method; however, concerns remain about errors of generalization, between both methods and laboratories. In this study, we used retrospective laboratory data to investigate the relationship between TTG2 antibody levels and Marsh 3 histology in the seropositive population of adults and children at a single centre. Among 202 seropositive patients with corresponding biopsies, it was possible to define a TTG2 antibody cut-off with 100% specificity for Marsh 3 histology, at just over 10 × ULN for the method. However, UK National External Quality Assurance Scheme returns during the study period showed a wide dispersion of results and poor consensus, both between methods and between laboratories using the same method. Our results support the view that high-titre TTG2 antibody levels have strong predictive value for villous atrophy in adults and children, but suggest that decision cut-offs to guide biopsy requirement will require local validation. TTG2 antibody assay harmonization is a priority, in order to meet the evolving requirements of laboratory users in this field.

Serological testing for coeliac disease in Type 1 diabetes mellitus: is immunoglobulin A level measurement necessary?

AIMS

Immunoglobulin A (IgA) measurement is advocated when case finding for coeliac disease in patients with Type 1 diabetes mellitus. Currently, there is a paucity of contemporary studies assessing IgA deficiency in Type 1 diabetes. This study evaluates the prevalence of IgA deficiency in individuals with Type 1 diabetes, compared with patients with coeliac disease and control subjects. In addition, we evaluate whether routine IgA measurement is justifiable when case finding for coeliac disease in patients with Type 1 diabetes.

METHODS

All patients were assessed using IgA endomysial antibodies, IgA anti-tissue transglutaminase antibodies and total IgA levels. Altogether, 2434 individuals were tested: 1000 patients with Type 1 diabetes, 234 patients with coeliac disease and 1200 population control subjects. Definitive IgA deficiency was defined as total IgA levels < 0.07 g/l.

RESULTS

The prevalence of IgA deficiency was significantly more common in patients with Type 1 diabetes (0.9%, n = 9/1000; P = 0.036) and coeliac disease (1.29%, n = 3/234; P = 0.041) when compared with population control subjects (prevalence of 0.17%, 2/1200). No statistical difference between Type 1 diabetes and coeliac disease for IgA deficiency was identified (P = 0.87). Of patients in the group with Type 1 diabetes, 3.3% (33/1000) had coeliac disease, and of those only one patient had IgA deficiency leading to an antibody-negative presentation. Both IgA-deficient individuals within the population control subjects had normal duodenal biopsies and no relevant symptoms.

CONCLUSIONS

IgA deficiency is more common in Type 1 diabetes compared with population control subjects. Despite this, very few individuals with Type 1 diabetes and IgA deficiency appear to have villous atrophy on biopsy. These outcomes question the practice of routine IgA measurement when case finding for coeliac disease in patients with Type 1 diabetes.

Defining the impact of individual sample variability on routine immunoassay of serum free light chains (sFLC) in multiple myeloma

Serum free light chain (sFLC) measurement has gained widespread acceptance and is incorporated into various diagnostic and response criteria. Non-linearity and antigen excess are the main causes of 'variability' in the measurement of sFLC using immunoassay, but the impact of these on measurement has been unclear. We performed a retrospective evaluation using a dilutional strategy to detect these phenomena. A total of 464 samples in 2009 and 373 samples in 2010 were analysed for sFLC. Non-linearity was detected in both high and apparently normal sFLC. Major non-linearity of more than twofold is common in high kappa (20·2%) and lambda (14·1%). It is less common in samples with apparently normal levels - kappa (6·4%) and lambda (9·5%). 9·4% of kappa and 15·5% of lambda showed antigen excess at screening dilutions. 34·4% of the samples had either non-linearity or antigen excess. We conclude that significant measurement variability is common in the measurement of sFLC. There is currently no reliable technique to detect non-linearity phenomena unless a serial dilution strategy is applied to every analysis. We recommend that laboratories routinely reporting sFLC results for clinical services need appropriate strategies for addressing these issues. Clinicians should be aware of these limitations in interpretation of sFLC assay for individual patients. Future guidelines should adopt action thresholds which are grounded firmly in test performance parameters.

Quality not quantity for transglutaminase antibody 2: the performance of an endomysial and tissue transglutaminase test in screening coeliac disease remains stable over time

National Institute of Clinical Excellence (NICE) and European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidance for the diagnosis of coeliac disease has been published. However, there is some controversy regarding the advice on the use of stratifying levels of immunoglobulin (IgA) tissue transglutaminase antibody (TG2) test positivity in the absence of test standardization and the vagueness of the indication to test equivocal samples. Using repeat service audit, we demonstrate that a combination of TG2 followed by IgA endomysial antibodies (EMA) is the best strategy for all degrees of mucosal abnormality using our test combination. Reliance upon immunoassay titre is not as effective, and cannot be applied consistently across populations in the absence of assay standardization. Guidelines advocating the use of tests should involve experts in laboratory diagnostics and external quality assurance to ensure that errors of generalization do not occur and that test performance is achievable in routine diagnostic use.

Raised tryptase without anaphylaxis or mastocytosis: heterophilic antibody interference in the serum tryptase assay

Mast cell tryptase (MCT) is a key diagnostic test for mastocytosis and anaphylaxis. High serum tryptase levels are also one of the risk factors for adverse reaction in venom immunotherapy, yet occasional patients are seen with raised levels in the absence of either diagnosis. False positive results can be due to assay interference by heterophilic antibodies such as rheumatoid factor (RF) and human anti-mouse antibodies (HAMA). We therefore investigated heterophilic antibody interference by rheumatoid factor activity and HAMA as a cause of raised MCT results in the Phadia tryptase assay. Serum samples from 83 patients were assayed for MCT and rheumatoid factor before and after the use of heterophilic antibody blocking tubes (HBT). Samples with more than 17% reduction in MCT with detectable RF were then assayed for HAMA. Fourteen (17%) of the 83 samples with positive RF showed a >17% decrease in mast cell tryptase after HBT blocking. Post-HBT, eight of 14 (57%) reverted from elevated to normal range values with falls of up to 98%. RF levels were also decreased significantly (up to 75%). Only one of the 83 tested was apparently affected by HAMA in the absence of detectable IgM RF. In conclusion, any suspicious MCT result should be checked for heterophilic antibodies to evaluate possible interference. False positive MCT levels can be caused by rheumatoid factor. We suggest a strategy for identifying assay interference, and show that it is essential to incorporate this caveat into guidance for interpretation of MCT results.

NOD2 polymorphisms in clinical phenotypes of common variable immunodeficiency disorders

Common variable immunodeficiency disorders (CVIDs) are a heterogeneous group of diseases characterized by hypogammaglobulinaemia and consequent susceptibility to infection. CVID patients commonly develop a variety of additional manifestations for which the causative factors are not fully understood. Two such manifestations are granulomatous disease and enteropathy. Because the ability to predict complications would aid clinical management, we continue to search for possible disease modifier genes. NOD2 acts a microbial sensor and is involved in proinflammatory signalling. Particular mutations of the NOD2 gene are associated with Crohn's disease including gly908arg, leu1007finsc and arg702trp polymorphisms. We hypothesized that NOD2 polymorphisms may be a disease modifier gene towards an enteropathic or granulomatous phenotype within CVIDs. Sequence-specific primers returned genotypes for 285 CVID patients from centres across the United Kingdom and Europe. We present the frequencies of the different phenotypes of patients within our international cohort. Arg702trp polymorphisms were significantly less frequent than wild-type (WT) (P = 0·038) among international CVID patients with splenomegaly. Gly908arg polymorphisms were more prevalent than WT in UK patients with autoimmune disorders (P = 0·049) or enteropathy (P = 0·049). NOD2 polymorphisms were not more prevalent than WT in CVID patients with clinical phenotypes of granulomata. UK allele frequencies of 0·014, 0·056 and 0·026 were found for gly908arg, arg702trp and leu1007finsc NOD2 polymorphisms, respectively. These do not differ significantly from UK immunocompetent controls confirming, as expected, that in addition these NOD2 polymorphisms do not confer susceptibility to CVIDs per se.

Survey of clinical allergy services provided by clinical immunologists in the UK

BACKGROUND

The UK National Health Service is failing to meet the need for diagnosis and treatment of allergic disorders, which are common and increasing in prevalence. The House of Commons select committee report on allergy services highlighted the inequalities and urgent need for investment.

AIM

To survey the allergy workload provided by clinical immunologists to inform service planning and resource allocation.

METHODS

The allergy services performed by clinical immunologists during a 12 month period from 1 April 2003 to 31 March 2004 were surveyed by means of a questionnaire via supra-regional audit groups.

RESULTS

The immunology centres surveyed serve 32 million people and offer almost the complete repertoire of a specialised allergy service. There were large variations in clinic capacity, new referrals, appointment duration, and service configuration. Services were largely consultant delivered, but availability of joint clinics with paediatricians and anaesthetists was locally variable. Novel service delivery models utilising nurses and clinical assistants have been developed and merit further investigation.

CONCLUSION

Consultant immunologists and trainees currently make a major contribution to the development and provision of specialised allergy services. Consultant immunologists will probably remain key providers of tertiary level allergy care in the UK in the long term (in line with other countries) and will be pivotal in supporting and developing the provision of equitable national access to specialist allergy services in a timely manner. Rapid progress in developing the new specialty of allergy and securing better access to services for patients in the short term will be best served by strengthening the collaborative relationship between allergists and clinical immunologists.

Do serum levels of eosinophil granule-derived protein change in patients undergoing pelvic radiotherapy?

AIMS

Eosinophils have an important role in the pathogenesis of inflammatory bowel disease, with faecal levels of the eosinophil granule proteins, eosinophil cationic protein (ECP) and eosinophil protein X (EPX) reflecting disease activity. Eosinophil crypt abscesses are a characteristic histological finding in acute gastrointestinal radiation-induced mucosal damage. This pilot study aimed to investigate changes in serum levels of ECP/EPX during pelvic radiotherapy.

MATERIALS AND METHODS

Patients with no history of inflammatory bowel disease, starting a 5-week course of pelvic radiotherapy, had serum ECP/EPX levels measured before radiotherapy and during the fourth week of treatment. Bowel toxicity was graded at week 4 using the Common Toxicity Criteria Scale.

RESULTS

Fifteen patients who were to undergo adjuvant radiotherapy for gynaecological cancer were recruited. The mean serum levels of ECP and EPX before treatment were 17.3 microg/l (range 2.0-49.3 microg/l) and 37.3 microg/l (range 12.0-94.0 microg/l), respectively. The mean serum levels during week 4 of radiotherapy for ECP and EPX were 43.0 microg/l (range 2.4-164.0 microg/l) and 38.7 microg/l (range 9.0-79.0 microg/l), respectively. Serum ECP levels increased at week 4 compared with levels before radiotherapy (P = 0.02). Acute bowel toxicity was seen in 12 patients (80%) at week 4: Grade 1 in 25% patients and Grade 2 in 75%. In this small study, no correlation was seen between acute bowel toxicity at week 4 and serum ECP or EPX levels.

CONCLUSIONS

Serum ECP levels increase in response to pelvic irradiation. This may reflect the known involvement of eosinophils in the acute response to radiotherapy. Further study is required to determine when levels start to rise and their relationship to the degree of acute bowel toxicity.

The national survey of adverse reactions to dental materials in the UK: a preliminary study by the UK Adverse Reactions Reporting Project

OBJECTIVE

Dental treatment involves the use of a wide range of materials. Many of the dental materials or their components pose a potential risk to the patient and member of the dental team. Pre-market biocompatibility testing cannot guarantee absolute safety, making monitoring of materials likely to cause an adverse reaction essential. The prevalence of adverse reactions to dental materials amongst dental patients and staff has not been systematically monitored in the UK. This project aims to develop a systematic approach to the evaluation and monitoring of the extent and severity of adverse reactions to dental materials in the UK.

METHOD

Through the distribution of reporting forms to dental surgeries and laboratories in the UK, the ARRP has received 1,075 complete reports relating to adverse reactions seen or experienced by dental staff and patients.

RESULTS

The main findings were that different materials cause adverse reactions to different groups of people. The largest proportion of patient related adverse reactions were reported to be due to metals (n = 175). These were mainly amalgam associated oral lichenoid reactions (n = 124). Dental technicians reported acrylic resin as the causal factor of hand dermatitis in 61% (44 out of a total 72) of cases reported. Finally, dental surgery staff reported gloves as causing hand dermatitis in 75% of cases (398 out of a total 531).

CONCLUSIONS

Different dental materials affect different person groups depending on their exposure to the material. Dental staff are most at risk from an adverse reaction to latex gloves, whereas most reported reactions for patients were due to metals. For dental technicians the biggest danger of an adverse reaction was from acrylic resins. There is a need to continue to raise the awareness among dental professionals of the existence of the Adverse Reactions Reporting Project so as to overcome problems of under-reporting.

Adverse reactions to protective gloves used in the dental profession: experience of the UK Adverse Reaction Reporting Project

The Adverse Reaction Reporting Project (ARRP) was set up to measure the extent and severity of adverse reactions to dental materials in the UK. Further analysis into the use of protective gloves has been carried out to establish the degree to which gloves are having a deleterious effect on the dental profession. In addition the survey aimed to establish the techniques used to manage adverse reactions and their effectiveness. In a 23-month period, 369 reports were received concerning adverse reactions to protective gloves used in dental practices. Reporters were contacted for further information, and a 92% response rate was achieved. The 330 reports analysed showed dentists to be the largest group to report adverse reactions, whilst dental technicians reported the fewest. The referral rate for staff and patients was similar with a third of adverse reactions being referred (n=110) to a specialist for diagnosis. A confirmed diagnosis was received in 65% of referred cases (n=72), but the symptoms reported suggested a larger degree of Type I reactions occurring than diagnosed. The use of non-powdered gloves appeared to be favoured over powdered gloves in 42% of glove changes, and nitrile gloves were used as an alternative to latex in 39% of changes. In conclusion, the results from this survey showed that wearing gloves in dental practices in the UK caused a range of adverse reactions. In 79% (n=330) of cases reported and analysed, these reactions were readily resolved or improved by self-medication, prescribed medication and/or changing to a different type of protective glove.

Efficacy, tolerability, safety and pharmacokinetics of a nanofiltered intravenous immunoglobulin: studies in patients with immune thrombocytopenic purpura and primary immunodeficiencies

BACKGROUND AND OBJECTIVES

A nanofiltration step with the capacity to reduce blood-borne pathogens was introduced into the manufacturing process of intravenous immunoglobulin (IVIG). In order to demonstrate the efficacy, safety and pharmacokinetics of the modified product, we conducted Phase II/III studies comparing the nanofiltered IVIG (IVIG-N) with its parent product, Sandoglobulin, in patients with chronic immune thrombocytopenic purpura (ITP) and primary immunodeficiencies (PID).

MATERIALS AND METHODS

Patients with ITP (n = 27) with platelet counts of < 20 x 10(9)/l were treated with Sandoglobulin or IVIG-N infusions at a dose of 0.4 g/kg body weight on five consecutive days. The primary efficacy end-point was the number of patients with an increase in platelet counts to > 50 x 10(9)/l. Secondary end-points were time to and duration of response, and regression of bleeding. Patients with PID (n = 36) were treated for 6 months with Sandoglobulin or IVIG-N at doses of 0.2-0.8 g/kg, infused at 3- or 4-week intervals. The primary end-point was the number of days absent from school/work. Secondary end-points were hospitalization, use of antibiotics and feeling of well-being. In both studies, tolerability was assessed by recording of adverse events and laboratory determinations. Viral safety was ascertained by serology supplemented with nucleic acid detection methods. Pharmacokinetics were analysed in patients with PID using serum concentration-time data for immunoglobulin G (IgG), and IgG antibodies to hepatitis B surface antigen (anti-HBsAg).

RESULTS

In the ITP study, the primary end-point was met by 12/16 patients on IVIG-N and by 10/10 patients on Sandoglobulin (P = 0.123). A shift towards lesser bleeding intensity was seen in both groups. In the PID study, seven of 18 patients on IVIG-N and six of 16 patients on Sandoglobulin missed days at work/school, with monthly mean absences of 0.4 and 0.5 days (P = 0.805). The feeling of well-being was comparable in both groups. In the ITP study, adverse events with a causal relationship to medication were suspected in six patients on IVIG-N and in seven on Sandoglobulin. In the PID study, three patients on IVIG-N and two on Sandoglobulin experienced possible drug-related adverse events. In both studies, serological and polymerase chain reaction (PCR) tests gave evidence for virus safety. Pharmacokinetics showed constant peak and trough serum IgG levels in all patients, indicating almost steady-state conditions for both formulations. The overall half-life (t1/2) for total IgG was 33 +/- 17 days in the IVIG-N arm and 25 +/- 16 days in the Sandoglobulin arm; for anti-HBsAg t1/2, values were 17 +/- 7 and 17 +/- 9 days, respectively.

CONCLUSIONS

IVIG-N is efficacious, well tolerated and safe in patients with ITP and PID. Its pharmacokinetic properties were comparable to those of Sandoglobulin.

Detection of serum M2 anti-mitochondrial antibodies by enzyme-linked immunosorbent assay is potentially less specific than by immunofluorescence

AIM

To compare the predictive values of enzyme-linked immunosorbent assays (ELISAs) and indirect immunofluorescence (IIF) techniques for the detection of M2 anti-mitochondrial antibodies.

METHODS

Commercial ELISAs are widely available for the detection of anti-mitochondrial antibody subtypes in primary biliary cirrhosis (PBC). We compared the results from two ELISAs (one recombinant, one purified antigen) with those from two IIF methods in a well-defined cohort of PBC patients and in patients with systemic lupus erythematosus, Sjögren's syndrome, sicca syndrome, systemic sclerosis, rheumatoid arthritis and blood donor controls.

RESULTS

There was good correlation between a rodent substrate IIF and ELISA A (r=0.9134), but poor correlation with ELISA B (r=0.5999), which produced many false-positive results in the control population. We show that rodent IIF alone or human epithelial cell (HEp-2000) screening with confirmation by ELISA produce similar predictive values for PBC and require lesser degrees of skilled interpretation of IIF patterns.

CONCLUSIONS

We conclude that the specificities of IIF are greater than the ELISA methods (99% versus 85-97%), although the ELISAs are slightly more sensitive in biopsy-proven PBC. Careful in-house validation of all new ELISA technologies is mandatory for good laboratory practice, but IIF in experienced hands remains an effective and specific assay.

Antibody responses to vaccinations given within the first two years after transplant are similar between autologous peripheral blood stem cell and bone marrow transplant recipients

As a consequence of the significantly larger inoculum of lymphoid cells present in peripheral blood stem cell (PBSC) harvests compared to bone marrow (BM), it is possible that autoPBSCT recipients may have an earlier and*or enhanced response to vaccines. Until data to confirm this become available, the European Blood and Marrow Transplantation Association (EBMT) recommend that all transplant recipients be immunized in the same way regardless of stem cell source. We performed a prospective study comparing serological responses to influenza, pneumococcal polysaccharide and tetanus toxoid vaccines between autoPBSCT with autoBMT recipients. Antibody responses in sibling HLA-matched allogeneic BMT (alloBMT) survivors were also evaluated. All vaccines were administered within the first 2 years after stem cell transplantation. Fifty patients were enrolled. The time of vaccination after transplant was similar between autoPBSCT (mean 11 months for each vaccine) and autoBMT recipients (mean 12 months except 13 months for tetanus toxoid) (P = NS). Serological responses were poor and no significant difference in response to any of the vaccines used was seen between the three transplant cohorts. We provide no evidence that current EBMT guidelines be modified. Large prospective vaccine studies are needed to address the issue more fully.

Two episodes of life-threatening anaphylaxis in the same patient to a chlorhexidine-sulphadiazine-coated central venous catheter

Chlorhexidine allergy has been described in the literature, mainly in Japanese individuals. Most reactions have been limited to the skin, mild in severity and a result of chlorhexidine containing solutions such as 'Savlon' (Novartis Consumer Health, Horesham, UK). We describe what we believe is the first reported case of anaphylaxis in a European patient to a chlorhexidine- sulphadiazine-coated central venous catheter.

Assessment of latex allergy in a healthcare population: are the available tests valid?

BACKGROUND

Latex allergy can cause serious, preventable work-related health problems in healthcare workers who are a high risk group for this form of allergy. Type I hypersensitivity can produce life-threatening systemic effects, and involves an allergen-specific immunoglobulin (IgE) response to proteins found in latex. The estimated prevalence of latex 'allergy' in healthcare workers varies widely (2.8% - 18%), and studies do not always distinguish between those who are positive in an assay for latex-specific IgE and those with clinical allergy.

OBJECTIVE

To assess the performance of four in-vitro methods and three skin testing methods for detecting latex-specific IgE in a group of UK healthcare workers. Test results were compared with reported clinical symptoms defined by questionnaire.

METHODS

Skin prick testing was carried out on volunteers using three reagents: (a) stallergenes commercial latex extract (Cedex, France); (b) an in-house latex glove extract; and (c) a fresh glove piece. Specific IgE levels were determined using Pharmacia AutocapTM (Uppsala, Sweden), Pharmacia UnicapTM (Uppsala, Sweden), DPC Immulite(R) (Los Angeles, USA) and Hycor HytecTM (Irvine, California, USA) methods. Each volunteer completed a questionnaire detailing latex exposure and allergic history.

RESULTS

In vitro methods for detecting specific IgE to natural rubber latex were positive in 3.6%, to 43.6% of the same population. Skin prick tests positivity varied between 2. 9% and 14.3% with different extracts. From the subjects tested 9.1% reported symptoms which could be consistent with type I allergy, although none had been given a pre-existing diagnosis of latex allergy, and 43.6% of volunteers reported symptoms consistent with type IV hypersensitivity or irritant dermatitis. Contingency tables and chi-squared analysis revealed no correlation between most methods. No correlation was shown between symptoms consistent with type I allergy and any in vitro or skin testing method for latex-specific IgE.

CONCLUSIONS

A wide variation between testing procedures was found, and no method could be correlated with reported symptoms of type I allergy. At least one in vitro specific IgE assay produced a high percentage of positive results at variance with the clinical symptoms in volunteers. A clinical history is essential in establishing type I hypersensitivity to latex and test results should not be used in isolation. The incidence of clinical sensitization may be seriously over-estimated if only laboratory parameters are used.

The use of laboratory tests in the diagnosis of SLE

ANA IIF is an effective screening assay in patients with clinical features of SLE and will detect most anti-ssDNA, anti-dsDNA, ENAs, and other autoantibodies. False positives are common. The clinical importance cannot be extrapolated from the ANA titre or pattern, although higher titres (> 1/160) are more likely to be important. HEp-2 cells are the most sensitive substrate for ANA detection, but this must be balanced against an increased incidence of insignificant positivity. ANA positive samples should be subjected to more specific assays for the diagnosis of SLE. A combination of ENA (Ro/La/Sm/RNP) and dsDNA assays will detect most patients with SLE as long as the characteristics of the assays used are well understood. ESR and CRP measurements provide useful additional information. Sjogren's syndrome and MCTD will produce overlapping serology with SLE, and anti-dsDNA titres are sometimes seen in autoimmune hepatitis and rheumatoid arthritis. All results should be reported in the light of the clinical details, by an experienced immunologist. A suggested diagnostic protocol is outlined in fig 1. The type of assay used crucially influences the predictive value of the tests. ELISA technology dominates routine laboratory practice, but tends to produce more false positive and true weak positive results, which may reduce the PPV of the test. This can be minimised by using IgG specific conjugates and careful assay validation. The NPV for SLE [figure: see text] is high for most assays but the PPV varies. Where necessary, laboratories should use crithidia or Farr dsDNA assays to confirm dubious ELISA dsDNA results, and ID/IB to confirm dubious ENA results. For monitoring, a precise, quantitative assay is required. It is unclear whether the detection of IgM or low affinity antibodies has a role here. A combination of anti-dsDNA, C3, C4, CRP, and ESR assays provides the most useful clinical information. Anti-ssDNA assays are likely to be useful, and are potentially more robust than anti-dsDNA assays, but require more validation. Local validation of individual assays and EQA participation is essential. Not all assays that apparently measure the same antibody specificities have equal clinical relevance, even within a single technology. Insufficient international or national reference preparations are currently available for many antibody specificities to enable effective standardisation. Quality assurance schemes reveal large differences in units reported by different assays for some analytes, even when calibrated against an IRP or equivalent reference preparation. Serial results can therefore only be compared from the same laboratory at present. Most autoantibodies increase during active disease, but few prospective data are currently available to justify treatment on the basis of rising titres. Further randomised prospective studies are required to examine the importance of antibody isotype and affinity in the monitoring of SLE by individual assay methods. The most important aspect of the appropriate use of laboratory assays is to become familiar with the limitations of the technology currently in use in your local laboratory, and to consult with your clinical immunologist in cases of doubt, preferably before commencing serological screening.

The frequency and clinical significance of specific IgE to both wasp (Vespula) and honey-bee (Apis) venoms in the same patient

BACKGROUND

Changeover from Phadebas RAST to Pharmacia AutoCAP increased double-positivity to both honey-bee and common wasp (vespula) venom in our patients.

OBJECTIVE

We examined the frequency of IgE double-positivity, its clinical relevance and utility in investigating potentially allergic patients.

METHODS

One hundred and eighty-two patients with hymenoptera allergy were tested using RAST (n = 51) and AutoCAP (n = 131) assays over 4 years. Patients had a history of reactions to vespulae (22), honey-bee (10) and unidentified hymenoptera (vespinae) (7).

RESULTS

After changing from RAST to AutoCAP double-positivity increased from 10 (5/ 51) to 30% (39/131) (P < 0.01). RAST and CAP assays gave similar median class results (vespula = 3, honey-bee = 2). Thirty-six CAP patients had systemic reactions of Mueller grade II and above. In vespula-allergic double-positive subjects, high CAP classes (> or = class 3) to honey-bee were common (30%). In 25% the CAP classes were equal. In honey-bee-allergic subjects, all vespula venom CAP IgE was low titre (class 1 or 2) and 20% were equal for both venoms. In 43% of vespinae-allergic patients the CAP class was equal to both (class 2 and 3). In contrast, intradermal skin test double-positivity was uncommon. Double-negative skin test results were common in the CAP double-positive population (22% of honey-bee-allergic, 13% of vespula-allergic and 43% of vespinae-allergic patients). Vespula allergic patients have higher bee-venom IgE than vice versa. Twenty-seven per cent of CAP double-positive patients (representing 8% of all venom allergic patients tested over this period) had equal class IgE to both venoms which was not helpful in diagnosis. Combination of skin testing and CAP is unhelpful in only 5/37 (14%) of patients with double-positive serology.

CONCLUSION

If used in isolation CAP may be misleading, especially if only one venom is tested. Identification of the causative venom must utilize both clinical history and skin testing in these double-positive patients, and challenge testing if indicated.

Incidence, character and clinical relevance of mixed cryoglobulinaemia in patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection has been implicated in the pathogenesis of mixed cryoglobulinaemia. Several studies have shown the presence of anti-HCV antibodies and HCV-RNA in both sera and cryoglobulins of such patients. However, the prevalence and clinical significance of cryoglobulins remain uncertain in patients with chronic HCV infection. We have studied 113 consecutive patients referred for assessment because of the presence of anti-HCV antibody in serum for the presence of cryoglobulinaemia and ascertained their clinical relevance and immunochemical properties. Twenty-one of 113 (19%) had detectable cryoglobulins with a mean protein concentration of 0.38 g/l (range 0.15-3.34 g/l). Most of these patients were asymptomatic. The cryoglobulins were of type III in 19 (91%) and of type II in two patients (9%). The latter two patients had the highest concentration of cryoglobulins, subnormal C4 and C1q levels suggesting classical pathway activation and vasculitis with renal impairment. The cryoglobulin IgG subclasses were mainly IgG1 and IgG3. HCV-RNA was detected more frequently in the sera of cryoglobulin-positive patients than in cryoglobulin-negative patients. This study showed that mixed cryoglobulinaemia is common in chronic HCV infection, and is predominantly type III. Evidence of systemic or renal disease was rare except in those with type II cryoglobulinaemia, and this may reflect either the concentration of the cryoprecipitate or the presence of a monoclonal complement-activating IgM paraprotein. The detection of HCV-RNA in the majority of the cryoprecipitates further supports the important role of HCV in the etiopathogenesis of essential mixed cryoglobulinaemia, although the mechanism is at present unclear.

Intercellular adhesion molecule-3 is the predominant co-stimulatory ligand for leukocyte function antigen-1 on human blood dendritic cells

Dendritic cells (DC) are potent stimulators of primary T lymphocyte responses to foreign antigen. The initial DC-T lymphocyte interaction involves the binding of the adhesion molecule leukocyte function antigen-1 (LFA-1; CD11a/CD18) on the T lymphocyte to an intercellular adhesion molecule (ICAM) on the DC. Although blood and tonsil DC express ICAM-1 (CD54) and ICAM-2 (CD102) on their surface, anti-ICAM-1 and anti-ICAM-2 monoclonal antibodies (mAb) have little inhibitory activity on the DC-stimulated mixed leukocyte reaction (MLR). We therefore examined the expression of the more recently identified LFA-1 ligand, ICAM-3 (CD50), in comparison to ICAM-1 and ICAM-2 on blood DC and sought a functional role for ICAM-3 in DC-mediated T lymphocyte responses. Resting blood DC expressed significantly more ICAM-3 than ICAM-1 or ICAM-2 as assessed by flow cytometry. Treatment of resting DC with interferon-gamma led to increased expression of ICAM-1; however, ICAM-2 and ICAM-3 levels remained relatively constant. Solid-phase recombinant chimeric molecules ICAM-1-, ICAM-2- and ICAM-3-Fc were able to co-stimulate CD4+ T lymphocyte proliferation in conjunction with suboptimal solid-phase CD3 mAb 64.1. However, the anti-ICAM-3 mAb CAL 3.10 inhibited a DC-stimulated MLR to a greater extent than anti-ICAM-1 or anti-ICAM-2 reagents and appeared to act by blocking the DC ICAM-3- T lymphocyte LFA-1 interaction. As ICAM-3 is the predominant LFA-1 ligand on resting blood DC, we postulate that DC may utilize ICAM-3 for initial DC- T lymphocyte interactions, and that ICAM-1, which is up-regulated upon DC activation, and/or ICAM-2, may contribute to DC migration or later phases of the T lymphocyte activation process.

The phenotype of freshly isolated and cultured human bone marrow allostimulatory cells: possible heterogeneity in bone marrow dendritic cell populations

Putative dendritic cells (DC) and their precursors have been obtained from human bone marrow but their origin and relationship to other myeloid cells remains obscure. A minor bone marrow mononuclear cell (BMMC) population, which contains the most potent allostimulatory cells and lacks mature cell lineage markers (CD3, CD11b, CD14, CD15, CD16, CD19, CD57 and glycophorin A; lineage-negative) was enriched by immunoselection. These preparations, which contain cells with similar characteristics to freshly isolated human blood DC, were further subdivided by serial fluorescent-activated cell sorting (FACS). Potent allostimulatory cells were detected in the CD34, CD33 and CD4 positive and negative subpopulations. Cells with putative DC morphology were present in both the CD33 and CD4 positive and negative fractions. No significant CD13 or Thy-1 staining was seen in the lineage-negative population. In vitro culture of lineage-negative BMMC for 7 days in conditioned medium resulted in a up to fivefold expansion of cells and generated many lineage-positive progeny. This lineage-positive population was as allostimulatory as the negative progeny. Likewise, the CD14-positive and the CD14-negative cell progeny were equally allostimulatory. In contrast, the freshly isolated lineage-positive BMMC (containing CD14-positive monocytes) remained poor stimulators of the mixed lymphocyte reaction (MLR), even after culture in the presence of cytokines. These data suggest that there are at least two phenotypically diverse forms of potent allostimulatory cells in the lineage-negative fraction of human BM, at least some of which express the early haemopoietic precursor antigens CD34 or CD33. Some of these precursors generate CD14-positive allostimulatory cells upon in vitro culture, suggesting an intimate link between DC ontogeny and myeloid differentiation.

Allostimulatory cells in fresh human blood: heterogeneity in antigen-presenting cell populations

The relative ability of unmanipulated monocytes, B cells, and dendritic cells (DC) from peripheral blood to stimulate an allogeneic MLR has not been clearly established. We studied the allostimulatory ability of these cell types from minimally manipulated PBMC populations to exclude the induction of stimulatory properties by the complex isolation procedures commonly used to isolate blood DC. Highly purified cell populations were obtained from volunteer donors by immunolabeling PBMC with mAb directed against known lineage-associated markers and separating the positive and negative population on a FACS. These cells were used as stimulators in an allogeneic MLR. The major allostimulatory activity resides in the CD14, CD11b, and CD19 negative fractions. A mixture of antibodies to T, B, NK, monocyte, and FcRIII positive cells was then used to isolate a minor cell population that contained a markedly superstimulatory population of (CD3, CD14, CD16, CD19, and CD57) negative cells. We demonstrate that this activity is constitutive, and is not an artifact of the adherence and in vitro culture steps used in conventional DC purification procedures. We also show by rigorous depletion of the T cell responders that endogenous HLA class II positive cells in the responder population have little role in presenting processed allogeneic antigens during the primary MLR. Monocytes and B cells are stimulators of the allogeneic MLR, but are considerably less potent on a cell for cell basis than the putative DC population. Finally, because human blood and tonsil DC lack detectable CD43 by immunoperoxidase staining, in contrast to monocytes and activated B cells, we examined the ability of CD43 negative and positive cells to stimulate an allogeneic MLR. Similar allostimulatory activity for the human MLR was shown to reside in both the CD43 positive and negative fractions, suggesting that there may be some heterogeneity in the APC population.

Identification of potent mixed leukocyte reaction-stimulatory cells in human bone marrow. Putative differentiation stage of human blood dendritic cells

Dendritic cells (DC) have been isolated from blood, lymphoid tissue, and other tissues, as potential members of a hemopoietic lineage of specialist APC for naive T lymphocyte activation. To define human bone marrow (BM) DC we have attempted to identify allostimulatory cells with DC-like characteristics among human BM mononuclear cells (BMMC) by FACS cell sorting and immunophenotyping, monitoring the APC function of different cell lineages in the human primary MLR. We show that fresh human BM stimulates allogeneic T lymphocytes with an activity equal to or greater than that of peripheral blood. As with DC from other tissue sources, the most potent stimulatory activity was found in the low density BMMC, and these cells, like peripheral blood, stimulated a maximal allogeneic MLR response at days 5 to 6. FACS purification of the allostimulatory population in fresh human BMMC was undertaken by using a wide range of mAb directed against lineage-associated molecules of mature and immature lymphoid, erythroid, and myeloid cells. The most potent constitutive BMMC stimulatory activity was located in the CD3-, CD11b-, CD14-, CD15-, CD16-, CD19-, CD57-, and glycophorin A- population. A mixture of antibodies to these Ag was used to isolate a "mix-negative" BMMC population, which contained the most highly potent MLR-stimulatory cells. Further cytologic and immunophenotypic analysis of this population revealed an enriched population of HLA-DP+, HLA-DQ+, HLA-DR+, and CD45+ cells, with morphologic similarities to the human tonsil and blood DC. These cells were CD4- and CD1a- and were weakly CD33+ (but CD15-), suggesting a possible early myeloid origin distinct from both the committed granulocytic and monocytic lineages. In addition, they lacked both CD10 and CD20, making a lymphoid origin unlikely. Further identification of these putative DC precursors will allow analysis of the early phases of DC hemopoiesis, whereas the characterization of the MLR-stimulatory cells in human BM will be of major importance in the understanding of BM transplant failure and graft-vs-host disease.

Identification of potent mixed leukocyte reaction-stimulatory cells in human bone marrow. Putative differentiation stage of human blood dendritic cells

Dendritic cells (DC) have been isolated from blood, lymphoid tissue, and other tissues, as potential members of a hemopoietic lineage of specialist APC for naive T lymphocyte activation. To define human bone marrow (BM) DC we have attempted to identify allostimulatory cells with DC-like characteristics among human BM mononuclear cells (BMMC) by FACS cell sorting and immunophenotyping, monitoring the APC function of different cell lineages in the human primary MLR. We show that fresh human BM stimulates allogeneic T lymphocytes with an activity equal to or greater than that of peripheral blood. As with DC from other tissue sources, the most potent stimulatory activity was found in the low density BMMC, and these cells, like peripheral blood, stimulated a maximal allogeneic MLR response at days 5 to 6. FACS purification of the allostimulatory population in fresh human BMMC was undertaken by using a wide range of mAb directed against lineage-associated molecules of mature and immature lymphoid, erythroid, and myeloid cells. The most potent constitutive BMMC stimulatory activity was located in the CD3-, CD11b-, CD14-, CD15-, CD16-, CD19-, CD57-, and glycophorin A- population. A mixture of antibodies to these Ag was used to isolate a "mix-negative" BMMC population, which contained the most highly potent MLR-stimulatory cells. Further cytologic and immunophenotypic analysis of this population revealed an enriched population of HLA-DP+, HLA-DQ+, HLA-DR+, and CD45+ cells, with morphologic similarities to the human tonsil and blood DC. These cells were CD4- and CD1a- and were weakly CD33+ (but CD15-), suggesting a possible early myeloid origin distinct from both the committed granulocytic and monocytic lineages. In addition, they lacked both CD10 and CD20, making a lymphoid origin unlikely. Further identification of these putative DC precursors will allow analysis of the early phases of DC hemopoiesis, whereas the characterization of the MLR-stimulatory cells in human BM will be of major importance in the understanding of BM transplant failure and graft-vs-host disease.

Hodgkin's disease cell lines: a model for interleukin-1-independent accessory cell function

The haemopoietic origins of the Hodgkin's disease (HD)-derived cell lines L428, KM-H2 and HDLM-2 remain controversial. Analysis of T-cell receptor (TcR) and Ig rearrangements cannot resolve this, and lineage promiscuity limits the interpretation of isolated surface antigen expression. Nonetheless the cell marker profile of L428 has similarities with human dendritic cells (DC), and L428 strongly stimulates in the mixed leucocyte reaction (MLR). We therefore undertook an extended immunophenotypic comparison of the HD lines with that recently defined for DC, prior to examining their ability to stimulate allogenic T lymphocytes, and comparing the molecular interactions involved with those of primary MLR stimulatory cells. The immunophenotype of the HD lines failed to establish either a lymphoid or monocytoid derivation. The profile of L428 appeared similar to the human DC. All three lines were potent stimulators in the primary MLR, and each expressed relevant adhesion and signal-transducing molecules important for co-stimulating T lymphocytes. Inhibition studies using monoclonal antibodies indicated similar contributions within HD line-T cell MLR to that documented in human tonsil DC-T cell MLR. The HD lines produced no detectable interleukin-1 (IL-1) by biological or immunological analysis. Moreover they stimulated allogeneic T lymphocytes in the presence of anti-IL-1 antibodies. Thus although IL-1 mRNA can be detected in both HDLM-2 and KM-H2 by polymerase chain reaction, these lines, and L428, share with DC the ability to stimulate allogeneic T lymphocytes in an IL-1-independent manner [corrected]. HD lines, particularly L428, may provide a standardized, reproducible, IL-1-independent model for dissection of the co-stimulatory requirements of the human primary MLR.

Titration of antibodies against neutrophil cytoplasmic antigens is useful in monitoring disease activity in systemic vasculitides

Titration of antibodies against neutrophil cytoplasmic antigens (cANCA), as detected by indirect immunofluorescence, is shown to be clinically useful for monitoring disease activity in Wegener's granulomatosis and microscopic polyarteritis. Ten patients were followed (eight from presentation) prospectively for up to 2 years; during this time there were six episodes of vasculitic relapse in four patients and five infective episodes and one pulmonary embolus in four patients. Titres of cANCA were markedly raised, both at presentation (1/32-1/2048) and at vasculitic relapse (1/125-1/1048) but not in infection or embolism (negative, 1/16). Thus the titre of these antibodies can distinguish nonvasculitic illness from vasculitic relapse, in contrast to C-reactive protein levels which were raised in both. Titres of cANCA fell gradually after vasculitic relapse, in keeping with the half-life of IgG (3 weeks). C-reactive protein is a better measure of recovery.

An open study of the efficacy and safety of single dose fosfomycin trometamol in treatment of hospitalised patients with urinary tract infection (pilot study)

Single dose fosfomycin trometamol (3 g) was used to treat 20 hospitalised patients with UTI. Tolerance was good or excellent in 19/20 patients; a satisfactory bacteriological outcome was recorded in 11/17 of patients with sensitive organisms and a satisfactory clinical outcome was noted in 12/16 symptomatic individuals.