Immunology News

Change to the Reference range and interpretation of Voltage-gated Potassium Channel (VGKC) Antibodies (28.10.16)

 

With effect from Friday 28/10/16, the reference range and interpretation of Voltage-gated Potassium Channel (VGKC) Antibodies will change to

  <69pmol/L Negative

  70-130pmol/L Equivocal

  >130pmol/L Positive

  Previously, results <100pm were interpreted as negative

  If you have any queries please contact Dr Sinisa Savic (Consultant Clinical Immunologist) x65567 or Anna McHugh (Clinical Scientist) x25550

 

Change to Reporting of anti-Tissue Transglutaminase antibody (Coeliac Screen) Results (19.5.14)

The Joint BSPGHAN and Coeliac UK guidelines for the diagnosis and management of coeliac disease in children were published in 2013.  To facilitate the use of these guidelines anti-tTG Ab results will be reported as a numerical value rather than as an interpretive result.  This change affects results for anti-tTG Ab for both paediatric and adult requests.  This change will be introduced from Monday 2nd June 2014.

Reference: Arch Dis Child 2013;98:806-811 Murch S, Jenkins H, Auth M, et al. 

The policy for testing for coeliac disease remains unchanged for both paediatric and adult patients: 

v Serum from patients with suspected coeliac disease will be assayed for IgA anti-tissue transglutaminase (tTg).  Anti-tTG Ab are detected on the Bioplex 2200 multiplex platform.  An IgA verification bead is included in this assay and is therefore able to detect patients who are IgA deficient which makes the requesting of IgA unnecessary.

 §  For all individuals over 6 years:

¨     Where only immunoglobulins are requested in addition to coeliac serology, IgA tTG ONLY will be performed as the first line test

¨     If this result raises the possibility of IgA deficiency, measurement of IgA will be undertaken, in addition to measurement of IgG endomysial antibodies.

§  For all individuals under 6 years:

¨     In addition to coeliac serology, immunoglobulin measurement will be performed.

¨     If the result identifies IgA deficiency measurement of IgG endomysial antibodies will be performed. 

v Samples positive for anti-tTg will be further tested for IgA anti-endomysial antibodies.

v Samples flagged on the Bioplex analyser to be potentially IgA deficient (fail the IgA verification bead test) will have immunoglobulin levels measured by nephelometry in order to detect IgA deficiency.

v Samples shown to be IgA deficient will be assayed for IgG anti-endomysial antibodies.  

v Requests for anti-gliadin antibodies will receive IgA anti-tTg.

 

Changes to reporting of Anti-Nuclear Antibody (ANA) results (11.2.13)

In July 2012 the multiplex flow based immunoassay on the Bioplex 2200 analyser replaced the previously used indirect immunfluorescence for ANA screening and DNA and ENA antibody enzyme immunoassays for determining the specificity of the ANA.

The Bioplex 2200 ANA assay can simultaneously detect the presence of autoantibodies to the following autoantigen specificities: DNA, Ro (SS-A) 60, Ro (SS-A) 52, La (SS-B), Sm, SmRNP, RNP-68kD, Scl-70, Jo-1, centromere (CENP-B), chromatin and ribosomal P.

 

Until now, only results of the overall interpretation of the ANA screen and DNA Ab results have been reported, with free text comments indicating the other ANA specificities if the result was positive.  As of 11.2.13 the ANA report will display results for all of the ANA specificities.

Cryoglobulin Policy Updated: 14.1.13

 

Changes to screening for systemic autoimuune disease (Anti-nuclear antibodies), and anti-CCP, anti-GBM and anti-cardiolipin antibody tests (July 2012):

Dear colleagues

The purpose of this letter is to inform you about forthcoming changes that will affect how we perform screening for the systemic autoimmune diseases. We are planning to introduce an automated multiplex analyser which will replace the current methods. Presently we use immunofluorescence (IF) to screen for Anti-Nuclear Antibodies (ANA). The positive samples are then tested for the disease specific autoantigens (dsDNA and ENA's) using separate solid-based immunoassays.

The multiplex analyser is a one step method that will automatically test for the disease specific autoantigens. This alternative way of testing has several advantages:

It will minimize detection of ANA that have no obvious clinical significance.

It will also allow us to process ever increasing number of samples with greater efficiency and improved turnaround time. We anticipate that for example a turnaround time for anti-DNA antibodies, which presently can take up to 2 weeks during very busy periods, will be reduced to a few days, with urgent samples available in even shorter time frames.

This method has now been running in a few other big centres in the UK and Europe for a considerable length of time and no major problems have been identified. We ourselves have conducted extensive comparison between the two methods, and found no significant difference in their ability to identify clinically relevant autoantibodies.

In rare instances where there is a strong clinical suspicion of underlying systemic autoimmune disease, but where the autoimmune screen by multiplex analyser produces negative results, we will retain the ability to perform additional IF tests. If these are required clinically, arrangements can be made after discussion with a senior member of the laboratory staff or one of the consultant medical staff.

Other autoimmune tests that will be performed by the new method include anti-CCP, anti-cardiolipin and anti-GBM antibodies. We anticipate that this method will also be used to measure anti-MPO and anti-PR3 antibodies in the near future after appropriate evaluation and comparison.

Below is a table that compares the numerical values determined by the two different methods for the quantitative tests. 

We are confident that this change will allow the laboratory to continue to deliver a high quality service and improve efficiency and turnaround times for users.

If you have any concerns regarding the above changes please contact a senior member of staff for further information:

 

Dr. Sinisa Savic

Consultant Clinical Immunologist

01132065567

Email: Sinisa.Savic@leedsth.nhs.uk

 

Dr. Philip Wood

Consultant Clinical Immunologist

01132067256

Email:philipwood1@nhs.net

 

Patrick Hollier

Operational Lead

Clinical Immunology

Old Medical School

Leeds General Infirmary

Great George Street

Leeds LS1 3EX

Tel: 0113 39 23554

email: patrick.hollier@leedsth.nhs.uk

 

Test Current Method Bioplex 2200 (multiplex)
Anti-dsDNA Ab Positive ≥50 IU/mL Positive ≥10 IU/mL
    Indeterminate 5-9.9 IU/mL
Anti-cardiolipin Ab Positive ≥17 GPL U/mL Low Positive ≥20-39.9 GPL-U/mL
    Medium Positive ≥40-79.9 GPL-U/mL 
    High Positive ≥80 GPL-U/mL 
Anti-CCP Ab Positive >10 U/mL Positive ≥3 U/mL
  Equivocal 7-10 U/mL  
Anti-GBM Ab Positive >10 U/mL Positive ≥1 AI
  Equivocal 7-10 U/mL  

 

Changes to Serum Free Light Chain assay: Introduction of a new test (Feb 2012)

We are planning to introduce an alternative method to measure the serum free light chains.  We have already done some preliminary work to compare the existing (Freelite) and the new (Siemens latex enhanced) assay.

The two methods are comparable in their ability to detect significant changes to the ratio of free light chains, however they produce somewhat different absolute values.  There is good agreement at the lower end of the range, but the methods are less comparable when very high levels of free light chain are measured.  There is no single conversion factor which could be used to directly compare the levels measured by one method to the other.  Therefore we are planning to run the two methods in parallel.  This is to allow you to gain some experience in interpreting potentially different levels of free light chains in new and existing patients, and to allow us to identify any major problems with the new assay.

Please contact Dr Sinisa Savis to discuss any comments and concerns you might have regarding this change (x65567).

Reference ranges:

 

 

Freelite – current assay

 

Siemens – new assay

 

Free Kappa (mg/L)

 

3.30 – 19.4

 

6.7 – 22.4

 

Free Lambda (mg/L)

 

5.71 – 26.3

 

8.3 – 27.0

 

K:L ratio

 

0.26 – 1.65

 

0.31 - 1.56

 

 

October 2011: Changes to our assay for MPO and PR3 quantitation in patients with positive ANCA antibodies.

Due to a change in manufacturing supply, we are obliged to change our assay for MPO and PR3 quantitation in patients with positive ANCA antibodies.  This assay has higher sensitivity and similar sensitivity to the previous test and therefore, for the purposes of diagnosis, the test is unchanged from our currently available test.  However, the numerical values will change and the new reference ranges are as follows with our current assays reference ranges shown in brackets beside these:-

 

MPO:  Negative          <3.5 IU/mL   (<7 U/mL)

 

            Equivocal        3.5-5 IU/mL  (7-10 U/mL)

 

            Positive           >5 IU/mL      (>10 U/mL)

 

PR3:    Negative          <2 IU/mL      (<7 U/mL) 

 

            Equivocal        2-3 IU/mL     (7-10 U/mL)

 

            Positive           >3 IU/mL      (>10 U/mL)

 

We intend to provide results from both assays for a one month period to allow comparisons to be made usefully.  We plan to implement this from 24th October 2011. 

If you have any questions or concerns please contact Dr P Wood (Philipwood1@lnhs.net or phone (0113) 2065526).

 

September 2010 Test and Tubes update

All of the Immunology tests on the Tests and Tubes database have now been reviewed and updated as appropriate. There is a link to the Tests and Tubes database on the Immunology home page. Follow the “List recent changes (last 30 days)” link on the main Tests and Tubes page for a list of all test entries that have been amended. The Tests and Tubes database indicates each departments test repertoire and is useful as a quick reference for test indications, sample requirements and interpretation of results.

 

Anti-Tissue transglutaminase antibody testing - Change to Policy: 19.7.10

Immunoglobulin requests and screening tests for celiac disease.

 

Changes to the Beta-2-microglobulin Reference Interval: 29.6.10

As of 29.6.10 the reference range for ß-2-microglobulin will change from 0.7 - 1.8mg/L to 1.09 - 2.53mg/L.

 

Rheumatoid Factor - cut-off change: 25.2.10

As of 25.2.10 the cut-off range for Rheumatoid Factor will change from <40IU/mL to <20IU/mL.

 

Cryoglobulin assay Update 9.7.09

Cryoglobulin assay Policy change

 

Immunoglobulins/Serum Electrophoresis Update 15.6.09

Policy on Immunoglobulins and Serum Electrophoresis June 2009

 

ANA Update 11.5.09

Weak Positive ANA

Introduction of Immunocap 250 for Autoimmune Serology

 

After an extensive period of evaluation, from the beginning of February we will be using a new fully automated diagnostic system called the Immunocap 250 for the measurement of some autoantibodies. The system is produced by Phadia diagnostics who supply the ELISA based diagnostics currently used for the same assays. We have been using Immunocap technology for 2 years for allergy

The autoantibody assays involved are anti-CCP, the ENA screen, specific ENAs - anti-Ro, La, RNP, Sm, Jo-1 and Scl-70 and the ANCAs; anti-MPO and Anti-Pr3. Because the same antigen preparations are used in the Immunocap that are used in the ELISAs, you should not see major changes. Indeed for those assays where we report results as positive or negative there should be no differences between results obtained by either technique. For quantitative assays i.e where we report results in arbitrary units/ml there could be differences in values because of the different detection methods. In most cases the new assay will give higher results.

 

Change to our assays for anti-MPO and anti-PR3 (18.3.08)

It is therefore extremely important for anti-MPO  and anti-Pr3, where patients are monitored using the assays, that care is taken during the change over period.  For new patients and in the future when existing patients have been monitored for a while using the new Immunocap assay there will be no problem.

However, the first result using the new assay may well be higher than that obtained with the earlier assay.

The laboratory will identify on the report forms when the change to use of the Immunocap has been made. We will also give interpretive comments on whether we believe that changes in values from the old to new assays are significant or not.

This is an important change which should markedly shorten turnaround times, improve accuracy and ease the strain on laboratory staff. If you have any questions or concerns please email Michael.Kerr@leedsth.nhs.uk or phone 01133922979.

 

Update on Anti-Nuclear Antibody Testing

Anti-nuclear antibody testing by indirect immunofluorescence remains an effective method for the detection of antibodies directed against nuclear antigens. We have previously, in order to ensure appropriate turnaround time for ANA requests, stopped the routine assessment of the ANA titre, allowing more rapid processing to follow-up testing for double-stranded DNA (dsDNA) antibodies, and extractable nuclear antigen (ENA) antibodies, including Ro, La, Sm, RNP and Scl70.

The purpose of this update is to inform users of our protocol for both initial and repeat testing of ANA, dsDNA and ENA antibodies.

Samples with no previous record of ANA testing will be screened using indirect immunofluorescence. We are confident that our current methodology detects clinically relevant ANA.

In the majority of cases, positive ANA will automatically be booked in for dsDNA and ENA testing, and additional tests such as Rheumatoid Factor, complement C3 and C4 may be added if not already requested. Results will be reported accordingly.

Negative ANA will NOT be processed for dsDNA and ENA testing UNLESS clinical details suggest that further screening would be clinically useful e.g. recurrent miscarriage.

 

Repeat testing:

Samples will be screened using indirect immunofluorescence.

Samples known to be ANA positive but NEGATIVE for dsDNA and ENA will NOT have dsDNA and ENA repeated unless

  • A change in clinical status is indicated on the request form.
  • OR the last dsDNA test was more than 6 months previously.
  • OR the last ENA test was more than 12 months previously

Samples known to be ANA positive and POSITIVE for dsDNA and/or ENA will ONLY have dsDNA and/or ENA repeated automatically in the following situations:

  • Change in clinical status indicated on the request form
  • The last dsDNA test was more than 1 month previously.
  • The last ENA test was more than 12 months previously

By prior arrangement with a senior member of the medical or scientific staff, ANA titres will be performed on patients with clinical disease in whom variation in ANA titre is a good indication of variation in disease severity.

We are confident that these protocols will allow assay quality and the clinical utility of these tests to be maintained, whilst allowing the laboratory to provide the results in an efficient and timely manner.

 

Letter: 14 February 2007

To: Immunology Service Users Re: Changes to Initial Testing of Immunoglobulin requests

As you are aware, all areas of the Trust are in the process of ensuring that they deliver a cost effective service within an increasingly limited resource. In the light of ever increasing numbers if requests at a time when laboratory budgets are decreasing and vacant staff posts are being frozen, we have decided that we must reassess are policy on acceptance or requests for a number of tests. Our aim is to focus all of our resources on tests which are likely to directly affect patient management.

After a survey of the previous year’s activity we plan to introduce changes in the way we will off investigation of immunoglobulin abnormalities. The proposed changes will not, we believe, adversely affect the clinical utility of the tests required. We intend to divide samples into two pathways, depending on the clinical details supplied:

1. If the request form indicates that identification or exclusion of a paraprotein in the serum (i.e. myeloma, MGUS etc) is required, the sample will be analysed by electrophoresis ONLY, with serum immunolglobulin quantification only undertaken if a paraprotein is identified. It is recommended that a urine sample is provided to the laboratory WITH the serum sample, to allow identification of free light chain (Bence Jones protein) in the urine if present.

2. Requests for immunoglobulins in the context of systemic inflammatory illnesses will be analysed by immunoglobulin quantification ONLY, with no electrophoresis. The majority of these requests from patients with inflammatory or infectious diseases are of low diagnostic specificity in diagnosis and management. Repeat samples will be analysed in the same way unless exclusion or identification of a paraprotein is required. We would hope you would carefully consider whether these assays are really necessary.

In order for appropriate decisions to be made in the laboratory we suggest that specific requests are made as outlined above.

We intend to implement these changes from January 2007.

If you have any questions or comments on the above changes, please do not hesitate to contact Professor Michael Kerr directly (Ext. 22979) or via the laboratory (Ext. 22587).

 


Page updated: 11/11/16 | Updated by: Anna McHugh

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