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.

Low immunoglobulin A levels detected via the tissue transglutaminase assay can reveal previously undetected monoclonal proteins.

Increased awareness of coeliac disease and the 2009 NICE guidance has led to an increase in patients being screened for Immunoglobulin A deficiency. We have shown previously that this provides an opportunity for the early identification of other underlying primary immunodeficiency, e.g. common variable immunodeficiency. In this context, the underlying gastrointestinal problem appears to be related to bacterial overgrowth. Here, we demonstrate that in addition this also provides an opportunity to reveal underlying secondary immunodeficiency due to other causes in patients with gastrointestinal presentation, notably lymphoproliferative disorders. In one 3-month period, of 60 cases reviewed for low Immunoglobulin A, we found four new paraproteins through this testing route; one symptomatic multiple myeloma, one asymptomatic multiple myeloma, one monoclonal gammopathy of uncertain significance and one in a known chronic lymphocytic leukaemia patient.

Laboratory clues to immunodeficiency; missed chances for early diagnosis?

Primary immunodeficiency is seen in an estimated one in 1200 people, and secondary immunodeficiency is increasingly common, particularly with the use of immunosuppresion, cancer therapies and the newer biological therapies such as rituximab. Delays in the diagnosis of immunodeficiency predictably lead to preventable organ damage. Examples of abnormal pathology tests that suggest immunodeficiency from all laboratory specialities are given, where vigilant interpretation of abnormal results may prompt earlier diagnosis. If immunodeficiency is suspected, suggested directed testing could include measuring immunoglobulins, a lymphocyte count and T-cell and B-cell subsets.

Multi-modal locomotion: from animal to application.

The majority of robotic vehicles that can be found today are bound to operations within a single media (i.e. land, air or water). This is very rarely the case when considering locomotive capabilities in natural systems. Utility for small robots often reflects the exact same problem domain as small animals, hence providing numerous avenues for biological inspiration. This paper begins to investigate the various modes of locomotion adopted by different genus groups in multiple media as an initial attempt to determine the compromise in ability adopted by the animals when achieving multi-modal locomotion. A review of current biologically inspired multi-modal robots is also presented. The primary aim of this research is to lay the foundation for a generation of vehicles capable of multi-modal locomotion, allowing ambulatory abilities in more than one media, surpassing current capabilities. By identifying and understanding when natural systems use specific locomotion mechanisms, when they opt for disparate mechanisms for each mode of locomotion rather than using a synergized singular mechanism, and how this affects their capability in each medium, similar combinations can be used as inspiration for future multi-modal biologically inspired robotic platforms.

A multicentre study comparing two methods for serum free light chain analysis.

BACKGROUND: Serum free light chain analysis is now well established in the investigation of monoclonal gammopathies. In the UK there has, until recently, been a single supplier of kits for such analysis. Recently, a second method using monoclonal antisera was introduced. We have compared the performance of these two kits in four routine laboratories. METHOD: Samples submitted for routine analysis (327 samples, 258 [79%] from patients with B-cell lymphoproliferative disease) for serum free light chains were tested by both technologies (Freelite, Binding Site and N Latex FLC, Siemens), according to the manufacturers' instructions. RESULTS: Qualitative data were available by both methods on 313 samples for serum free kappa chains and 324 samples for lambda free light chains. We found poor correspondence of 81% for kappa and 74% for lambda. Five percent of samples were significantly discordant in these assays. CONCLUSIONS: These assays perform very differently in clinical practice. They cannot be used interchangeably, especially if monitoring patient responses to therapy.

Immunoglobulin A deficiency on serological coeliac screening: an opportunity for early diagnosis of hypogammaglobulinaemia.

We present a serendipitous case of clinically significant pan-hypogammaglobulinaemia, diagnosed after routine serological testing for possible coeliac disease led first to identification of IgA deficiency (discovered as a low background in IgA-based routine serological screening), and subsequently to confirmed pan-hypogammaglobulinaemia (antibody immunodeficiency). Hypogammaglobulinaemia is a relatively rare diagnosis (estimated at 1 in 36,000), in which delayed diagnosis and treatment are associated with chronic organ damage including bronchiectasis. Routine serological testing for coeliac disease using the IgA anti-tissue transglutaminase (IgA TTG) test is in widespread use and provides an opportunity for early diagnosis of hypogammaglobulinaemia. Routine serological screening for coeliac disease may uncover IgA deficiency, and we suggest that all IgA-deficient cases identified should also be checked for antibody deficiency by quantifying the other immunoglobulins (IgG, IgM).

External hydrocephalus and subdural bleeding in infancy associated with transplacental anti-Ro antibodies.

BACKGROUND: The isolated finding of an unexplained chronic subdural haematoma in an infant may suggest non-accidental head injury (NAHI). The authors report a previously undescribed cause of multifocal chronic subdural haematoma in infancy which could result in a misdiagnosis of previous NAHI. METHODS: Two infants, aged 3 and 4 months of age, presented with progressively increasing head circumference measurements from birth. There was no history of encephalopathy. Retinal haemorrhages were not present. CT and MRI demonstrated bilateral subdural fluid collections over the frontal regions that were consistent with either chronic subdural haematomas or haemorrhagic subdural effusions. In view of the possibility of NAHI, child protection investigations were initiated. FINDINGS: In neither case did the child protection investigations raise concerns. Comprehensive investigations for known haematological and metabolic disorders associated with subdural haematomas or effusions in infants were all normal. In both cases the infant's mother had a history of Sjögren's syndrome and both infants had positive anti-Ro antibody at presentation. CONCLUSIONS: Transplacental acquisition of anti-Ro antibodies has been associated with external hydrocephalus. External hydrocephalus has been recognised as a predisposing factor for subdural haemorrhage. These are the first reported cases linking the presence of anti-Ro antibodies and external hydrocephalus with subdural fluid collections in infancy.

Pitfalls in the performance and interpretation of clinical immunology tests.

A broad overview, with examples, of the potential pitfalls encountered in the clinical immunology laboratory is presented. Illustrative examples and case scenarios are provided from autoimmunity, immunochemistry and cellular immunology, looking at both technical and interpretative pitfalls.

C1-inhibitor deficiencies (hereditary angioedema): where are we with therapies?

Hereditary angioedema, an autosomal dominant disorder, presents clinically as recurrent episodes of swelling. It results from either deficient production or function of C1 inhibitor. Acquired angioedema is associated with lymphoproliferative or autoimmune disease. Conventionally attenuated androgens and antifibrinolytics have been used for prophylaxis, both for the long term and presurgically. Fresh frozen plasma and plasma-derived C1 inhibitor concentrate have been used primarily for treatment of acute attacks. All have drawbacks in side effects or potential for infection transmission. New treatments (recombinant C1 inhibitor, icatibant, DX-88, and for acquired angioedema, rituximab) so far show good safety profiles. Early data suggest these may be effective treatment alternatives. The efficacy of current treatment and the potential held by newer agents that target specific elements in complement or kinin pathways are examined. Some agents are likely to have a wider role in treatment of other, more common, forms of angioedema.

Laboratory testing for C1 inhibitor deficiency: a comparison of two approaches to C1 inhibitor function.

BACKGROUND: C1 inhibitor deficiency may be hereditary or acquired. It is characterized by absent or poorly functioning C1 inhibitor. The disorder is rare, with prevalence estimated at 1/50,000. The very low incidence of the condition makes the sensitivity and specificity of assays used particularly important. Two different methods are commercially available to measure C1 inhibitor function. There are few data comparing these assays. METHODS: Two assays of C1 inhibitor function (C1 inhibitor-C1s complex formation or inhibition of C1 esterase cleavage of artificial substrate [colorimetric]) were compared in 71 patients (28 hereditary angioedema, 2 acquired angioedema and 41 controls). RESULTS: Qualitatively, the two assays showed good correspondence (92%). Six of 71 results were discordant. Correlation in quantitative terms was moderate (R = 0.81). CONCLUSIONS: Both assays show high sensitivity for hereditary/acquired angioedema. The colorimetric assay is more prone to false-positive results. However, clinical interpretation is not adversely affected.

C1 inhibitor deficiency: management.

This is the second of two articles on C1 inhibitor deficiency based on a recent UK consensus document covering its diagnosis and management in adults and children. This summary focuses on the management of the disorder including prophylaxis, emergency treatment and special situations such as pregnancy and dental care.

Life-threatening acute pulmonary haemorrhage in primary Sjögren's syndrome with cryoglobulinaemia.

We describe a woman with primary Sjögren's syndrome who presented with an acute pulmonary-renal syndrome resulting from cryoglobulinaemic vasculitis. Pulmonary manifestations of Sjögren's syndrome are relatively common, whereas overt pulmonary complications of cryoglobulinaemia are rare. Pulmonary haemorrhage is rare in either disorder. The combination of Sjögren's syndrome, cryoglobulinaemia, and acute pulmonary haemorrhage has not been previously reported.

Ataxia, peripheral neuropathy, and anti-gliadin antibody. Guilt by association?

Some authors contend that patients with idiopathic neurological disease who are also anti-gliadin antibody seropositive are gluten sensitive. However, anti-gliadin antibodies lack disease specificity being found in 10% of healthy blood donors. We report a study comparing anti-gliadin antibody with other food antibodies in patients with idiopathic ataxia (20), hereditary ataxias (seven), or idiopathic peripheral neuropathy (32). Patients were HLA typed. IgA anti-tissue transglutaminase antibodies (tTG) were measured. No case was positive for IgA anti-tTG making occult coeliac disease unlikely. HLA DQ2 and HLA DQ8 were found distributed equally across all patient groups and unrelated to gliadin antibody status. HLA DQ2 expressing, anti-gliadin antibody positive cases (so called "gluten ataxia") were rare in our clinics (four cases in 2 years from a population of 2 million). We conclude that coeliac disease per se is not commonly associated with either idiopathic ataxia or idiopathic peripheral neuropathy. Our study also casts doubt on the nosological status of "gluten ataxia" as a discreet disease entity. All food antibodies tested, particularly IgG, were a common finding in both ataxia and peripheral neuropathy groups. No particular food antibody was associated with any patient group. Food antibodies were equally common in hereditary ataxias. We conclude they are a non-specific finding.

C1 inhibitor deficiency: diagnosis.

This is the first of two articles on C1 inhibitor deficiency based on a recent UK consensus document covering diagnosis and management of the disorder in both adults and children. This paper focuses on diagnosis of this disorder.

Flow cytometric characterisation of cells of differing densities isolated from human term placentae and enrichment of villous trophoblast cells.

Cells were isolated from human term placentae by trypsinisation of fragments of chorionic villi and fractionation of cells on a Percoll density gradient into six layers. A panel of 10 monoclonal antibodies to antigens on or in trophoblast cells (placental alkaline phosphatase (PLAP), cytokeratin-7, beta-human chorionic gonadotrophin (beta-hCG), human leucocyte antigen-G (HLA-G)), leucocytes (CD45), monocytes, macrophages, dendritic cells, B cells (HLA class II), mesenchyme cells (vimentin), fibroblasts (fibroblast antigen) and nucleated cells excluding villous trophoblast (HLA class I, CD9) was used to characterise the cells by flow cytometry. For staining intracellular antigens (cytokeratin, vimentin, beta-hCG) the cells were first fixed and permeabilised. The upper two layers from the gradient (density 1.013-1.039 g/ml) contained predominantly PLAP-positive cells or fragments, probably derived from the syncytiotrophoblast. Cytokeratin-positive cells accumulated mainly in the layer of density 1.039-1.052 g/ml and comprised the majority of the cell types identified in this fraction. Few or no cells reactive with antibodies to beta-hCG or HLA-G were identified in any layer. Non-trophoblast cells were heavier, being present mainly at densities 1.052-1.079 g/ml (CD45, HLA class I, vimentin) and 1.066-1.092 g/ml (fibroblast). Fewer than 10% of cells in any layer were HLA class II- or CD9-positive. Further purification of trophoblast cells was by negative immunomagnetic separation with removal of CD45-positive cells and HLA class II-positive cells to less than 1%. On culture of the cells from each layer, those of density 1.039-1.066 g/ml exhibited characteristics of cytotrophoblast cells; they secreted high levels of human chorionic gonadotrophin and formed adherent multinucleate cells. This procedure enabled the selection and enrichment of cytotrophoblast cells and/or syncytiotrophoblast fragments that are suitable for cellular and molecular studies.

C1 inhibitor deficiency: consensus document.

We present a consensus document on the diagnosis and management of C1 inhibitor deficiency, a syndrome characterized clinically by recurrent episodes of angio-oedema. In hereditary angio-oedema, a rare autosomal dominant condition, C1 inhibitor function is reduced due to impaired transcription or production of non-functional protein. The diagnosis is confirmed by the presence of a low serum C4 and absent or greatly reduced C1 inhibitor level or function. The condition can cause fatal laryngeal oedema and features indistinguishable from gastrointestinal tract obstruction. Attacks can be precipitated by trauma, infection and other stimulants. Treatment is graded according to response and the clinical site of swelling. Acute treatment for severe attack is by infusion of C1 inhibitor concentrate and for minor attack attenuated androgens and/or tranexamic acid. Prophylactic treatment is by attenuated androgens and/or tranexamic acid. There are a number of new products in trial, including genetically engineered C1 esterase inhibitor, kallikrein inhibitor and bradykinin B2 receptor antagonist. Individual sections provide special advice with respect to diagnosis, management (prophylaxis and emergency care), special situations (childhood, pregnancy, contraception, travel and dental care) and service specification.

Subclinical hypothyroidism: a comparison of strategies to achieve adherence to treatment guidelines.

BACKGROUND: Subclinical hypothyroidism is an entity based on the laboratory findings of a raised serum thyrotrophin (TSH) concentration and a normal free thyroxine (FT(4)) concentration. Patients with subclinical hypothyroidism who also have anti-thyroid peroxidase (TPO) antibodies have a higher conversion to overt hypothyroidism than those without, and treatment with thyroxine is recommended. METHOD: We audited anti-TPO assay requests within two NHS Trust hospitals, against consensus standards, to ascertain whether a cascade approach to anti-TPO testing and direct advice leads to more appropriate prescribing of thyroxine in general practice. RESULTS: Our data show that where anti-TPO status was automatically tested for and clear advice for treatment given, >85% of patients were treated according to the standard required by the consensus document, with >90% of those recommended to be commenced on thyroxine actually doing so. In contrast, where anti-TPO was not routinely assessed, treatment was started in 46% of patients, without clear evidence that this was appropriate. CONCLUSION: In order to better advise clinicians and in accordance with the agreed protocol, laboratory-generated cascade testing for anti-TPO antibodies should be an integral part of the investigation of subclinical hypothyroidism, and reports should contain appropriate interpretation and advice.

Rapid diagnosis and characterization of acute promyelocytic leukaemia in routine laboratory practice.

The rapid diagnosis of the t(15;17)(q22;q21) promyelocytic leukaemia is important in the early introduction of targeted therapy with all-trans retinoic acid plus chemotherapy. It has been noted that these are usually myeloperoxidase (MPO)-positive and HLA-DR-negative with homogenous expression of CD33 and heterogeneous expression of CD13. We evaluated the use of immunophenotyping, morphology and cytogenetics in our own practice. Cascade testing, using cytoplasmic MPO expression in a high percentage of blast cells in bone marrow as the primary screen and PML (promyelocytic leukaemia protein) expression as the secondary confirmatory test, allowed rapid identification of the cases with t(15;17). This approach allows early instigation of appropriate therapy.

Echocardiographic abnormalities in primary antibody deficiency.

OBJECTIVE: To document cardiac abnormalities secondary to pulmonary disease in primary antibody deficiency. PATIENTS AND METHODS: A cross sectional audit study of patients from a regional immunology centre. Subjects undergoing two dimensional and Doppler transthoracic echocardiography were reviewed. Ventricular dimensions and function, valvular competence, and estimated pulmonary artery pressure were recorded. Data were compared with clinical variables, pulmonary function tests, and thoracic computed tomography data. RESULTS: Nineteen patients with common variable immunodeficiency and one with IgG(2) subclass deficiency were included, mean age at diagnosis 37.5 years, mean estimated diagnostic delay 10.94 years. Left ventricular impairment was found in 15% and right heart dilatation in 20%. Pulmonary hypertension (mean pulmonary artery pressure >25 mm Hg) was found in 45% (9/20), graded as moderate (40-60 mm Hg) in 44% of cases. Pulmonary function was obstructive in 47% (9/19). Fifty five percent of the patients with computed tomography data within the last five years (10/18) had confirmed bronchiectasis. Patients with right heart dilatation and/or moderate pulmonary hypertension (n = 6) had a more prolonged diagnostic delay (p = 0.04) and more severe lung disease. CONCLUSION: Echocardiographic abnormalities are common in primary antibody deficiency, associated with diagnostic delay and pulmonary complications. Pulmonary hypertension should be considered in those with severe lung disease and can be confirmed by echocardiography.