You frequently organize training for serum protein electrophoresis interpretation, what advice do you want to you deliver to clinical pathologists who start with the capillary technology?

The training must be done in several stages. The first is to understand the methodology well and to deal with the differences between the capillarys curve results and results obtained with gel electrophoresis techniques. This can be done in one day in a specialized laboratory or as part of a training course organized by the Company, Sebia. It is necessary to include this first training with some clinical cases to illustrate the different electrophoretic profiles and the

main interferences. The second step consists of practicing interpretations of several daily series (between 4 and 6 series of 50 profiles) in collaboration with a referring clinical pathologist. This step is facilitated by providing a list of typical interpretations that can cover almost 90 to 95 % of the profiles in our population. In this training, we must learn to define the profiles that require further explorations particularly by immunotyping. It is also necessary to adapt the interpretation of electrophoresis with regard to other biological parameters such as specific proteins

measurement. The final step sees a professional situation in which all the profiles that raise concerns are discussed with the referring trainer. You also use immunotyping in your laboratory, could you remind us of the principle of this technique?

Immunotyping test consists of a mixture of serum with a negatively charged antiserum directed against IgG, IgA, IgM, Kappa light chains and Lambda light chains. Thus the polyclonal and monoclonal targeted proteins are subtracted by immunodisplacement on the migration profile.

Dr BOUCRAUT, could you please introduce your laboratory?

The Immunology laboratory of AP-HM performs the full range of immunochemical protein explorations (blood, urine, CSF, cryoglobulins ...), autoimmune diseases explorations, allergy and functional analysis of immune cells, for the entire hospital group. It is linked with research teams who have a special interest in biomarkers and pathophysiology of neurological disorders.

Could you tell us how many years you have been using capillary electrophoresis as well as the importance of this technology in your lab?

We started using capillary electrophoresis in 2008. We perform approximately 25,000 analyses per year, performing several analysis runs daily and also interpretations. The first objective is to assess whether or not to carry out a complementary exploration of Immunotyping, this is dependent on the electrophoretic profile seen, the patient result history, the clinical context and other biological parameters. We carry a daily biological validation of results requiring complementary medical or laboratory investigations.

In your experience, what are the main advantages of this technique?

Our first reason for introducing this technology was the ability to automate this activity. Moreover, the capillary electrophoresis technique has a better resolution than gel electrophoresis; it enables the best peak quantification and improves medical follow-up thanks to very good reproducibility and the the ability to overlay curves.

Interview of Dr Boucraut – Immunology laboratory of the Conception Hospital - Marseille, France

The major interest of immunotyping in an hospital immunology laboratory

November 2017

Sebia Focus - N°17

Parc Technologique Léonard de Vinci 27 rue Léonard de Vinci

CP 8010 Lisses, 91008 EVRY Cedex France

Tel. : +33 (0)1 69 89 80 80 Fax : +33 (0)1 69 89 78 78e-mail : sebia@sebia.com

Immunology laboratory, Conception Hospital, Marseille

concentration greater than 200 mg /L. The technical advantage of immunofixation is linked to the ability to adapt serum dilutions to each track. Finally, in our laboratory we are particularly interested in peripheral neuropathies related to the presence of a monoclonal immunoglobulin of IgM isotype with autoimmune activity anti-MAG or anti-GD1b. These monoclonal IgM are present at low concentrations. By experience, these discrete monoclonal IgM are more easily viewable by immunofixation. Knowledge of the clinical context is therefore useful in adapting biological explorations.

In conclusion, what could you say to biologists who would hesitate to implement the immunotyping technique in their laboratory?

The transition to capillary electrophoresis and immunotyping firstly provides a gain in terms of human resources and secondly in terms of reproducibility and repeatability. It is useful, for some profiles, to have the data of the urinary immunochemical analyzes and the serum protein assays especially the free light chain measurements. In order to start the activity, it is useful to be trained, for example through a reference technical lab and to be able to refer to it’s expertise for specific cases that require an immunofixation control.

The interpretation is based on the comparison with the reference profile, without addition of antiserum, with those obtained with each antiserum. We need to observe with which antiserum the anomaly is subtracted.

Why did you choose to implement immunotyping in your laboratory? What does this technology of monoclonal anomalies typing bring you in your daily expertise?

Immunotyping, unlike immunofixation, is an automated technique. Previously, we performed immunofixation for some patients to rule out the presence of a monoclonal component. Since the introduction of capillary electrophoresis, which has a better resolution than gel electrophoresis, and the contribution of the free light chain assay which makes it possible to detect the free light chain components, an immunotyping analysis is carried out in 10 % of explorations. The visualization of the immunotyping profile helps us to quantify the peak(s).

When the monoclonal peak is visible on protein electrophoresis, is it easy to interpret the immunotyping?

With a well-experienced eye, it is relatively easy to interpret the immunotyping of monoclonal peaks. For immunofixation, the principle of interpretation is identical to the interpretation of electrophoresis. However, for the interpretation of immunotyping, it is necessary on one hand to observe the subtraction of the peak in the analysis of one of the heavy chain profile and one of the light chain profile and on the other hand the persistence of anomalies in the other tracks.

Coupled with the Immunotyping assay, you can use the immunofixation technique on agarose gel. Can you tell us what percentage of the immunotyping you need to confirm by immunofixation?

Immunofixation is rarely used; on average 1 case each 20 to 30 immunotyping analysis. This is the case when there is suspicion of rare monoclonal IgD or IgE whose analyses are not possible using immunotyping. This is also the case when we need to occasionally precisely describe an oligoclonal profile. Immunofixation is also performed with free light chain antiserum when we need to confirm the free light chain assays for a

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