Gamma heavy chain disease in a patient with rheumatoid arthritis – a laboratory evaluation

Introduction: Heavy chain diseases (HCD) are neoplastic proliferations of B cells which secrete truncated immunoglobulin heavy chains without associated light chains. Being rare and probably underdiagnosed diseases the aim of this report is to show an additional case of gamma heavy chain disease in a 48 year old female patient with rheumatoid arthritis focusing on the laboratory presentation. Materials and methods: Laboratory work-up included agarose gel electrophoresis (AGE), capillary zone electrophoresis (CZE), immunofixation and nephelometrically determined immunoglobulin and immunoglobulin subclasses of the patient’s serum. Urine samples were also subjected to immunofixation and to a SDS-PAGE with consecutive immunoblot. Results: Nephelometrically measured elevated IgG concentrations were noted in combination with a decreased gamma globulin region and an increased beta globulin region on AGE. A definite monoclonal spike was not identified on AGE but at least suspected on CZE; finally serum and urine immunofixation demonstrated a monoclonal gamma heavy chain devoid of any corresponding light chains confirming the diagnosis of HCD. Analysis of the gamma heavy chain (HC) with means of SDS-PAGE revealed proteins of 40 kD and 80 kD most likely presenting a truncated HC in its monomeric and dimeric form and possibly leading to the failure of IgG-subclass typing with the applied IgG subclass antisera. Conclusion: This case report illustrates a new case of gamma HCD demonstrating variable laboratory manifestations and therefore the need for heightened awareness concerning this disease when confronted with abnormal and discrepant protein profiles in routinely applied laboratory tests

Multicentre evaluation of the Boehringer Mannheim/Hitachi 917 analysis system

The new selective access analysis system BM/Hitachi 917 was evaluated in an international multicentre study, mainly according to the ECCLS protocol for the evaluation of analysers in clinical chemistry. Forty-three different analytes, covering 56 different methods enzymes, substrates, electrolytes, specific proteins, drugs and urine applications were tested in seven European clinical chemistry laboratories. Additionally, the practicability of the BM/ Hitachi 917 was tested according to a standardized questionnaire. Within-run CVs (median of 3 days) for enzymes, substrates and electrolytes were <2% except for creatine-kinase MB isoform and lipase at low concentration. For proteins, drugs and urine analytes the within-run CVs were < 4% except for digoxin and albumin in urine. Between-day median CVs were generally < 3% for enzymes, substrates and electrolytes, and < 6% for proteins, drugs and urine analytes, except for lipase, creatine kinase and MB isoform, D-dimer, glycosylated haemoglobin, rheumatoid factors, digoxin, digitoxin, theophylline and albumin in urine in some materials. Linearity was found according to the test specifications or better and there were no relevant effects seen in drift and carry-over testing. The interference results clearly show that also for the BM/Hitachi 917 interference exists sometimes, as could be expected because of the chemistries applied. It is a situation that can be found in equivalent analysers as well. The accuracy is acceptable regarding a 95–105% recovery in standard reference material, with the exception of the creatinine Jaffé method. Most of the 160 method comparisons showed acceptable agreement according to our criteria: enzymes, substrates, urine analytes deviation of slope ± 5%, electrolytes ± 3%, and proteins and drugs ± 10%. The assessment of practicability for 14 groups of attributes resulted in a grading of one–three scores better for the BM/Hitachi 917 than the present laboratory situation. In conclusion, the results of the study showed good analytical performance and confirmed the usefulness of the system as a consolidated workstation in medium-sized to large clinical chemistry laboratories

Anti-glycolipid antibodies in patients with neuropathy: A diagnostic assessment

Anti-glycolipid antibodies are associated with immune-mediated neuropathies and screening is often performed as part of the diagnostic assessment for patients presenting with peripheral neuropathy. We report our experience in testing for immunoglobulin (Ig) G and IgM anti-glycolipid (GM1, GM2, GM3, GM4, GD1a, GD1b, GD2, GD3, GT1a, GT1b, GQ1b, sulfatides) antibodies in 290 consecutive patients presenting with neuropathy. Anti-glycolipid antibodies were detected significantly more often (43%) in patients who were diagnosed with definite immune-mediated neuropathy than in patients without a final diagnosis of immune-mediated neuropathy (control group) (23%). With positive and negative predictive values of 22% and 90%, respectively, anti-glycolipid antibodies are not a very reliable diagnostic tool in early patient contact. Certain antibodies (IgM to GM2, GT1a and IgG to GM3, GD3 and GT1b) were equally or more prevalent in the control group; clinicians should be aware of this distribution when receiving positive screening results for these antibodies. Concomitant IgG and IgM reactivities were found for GM1, GM2, GD1b and sulfatides, and were detected more frequently in patients with definite immune-mediated neuropathies. (C) 2013 Elsevier Ltd. All rights reserved