FAQ

A. TransFix^® was developed by scientists working for UK NEQAS. This organisation is the External Quality Assurance (EQA) assessor for all pathological diagnostic laboratories in the UK. UK NEQAS also supports many other laboratories in Europe and beyond.

Whole blood is very unstable due to proteolytic degradation. The result is that blood samples older than 36 hours are no longer viable for flow cytometric examination. For the same reason unstabilised whole blood is unsuitable for use as an EQA sample.

TransFix^® was developed by UK NEQAS as a solution to this problem. When added to whole human blood it stabilises the profile and inhibits proteolytic deterioration.

TransFix: A clinical sample stabilising fluid for use in clinical haematology and immunology.
D. Barnett, V.Granger, A.G. Pockley, J.M.saxton, I storie, L.Whitby & J.T.Reilly
Cytometry (1999) 38:88 (abstract)

A. For HUMAN samples the ratio of TransFix^® to whole blood is 0.2ml per 1ml blood. Lower concentrations of TransFix^® can be used but will reduce the maximum period of stability. Early publications mention a concentration of 0.1ml per ml of blood being used. This does not equate with the concentration of TransFix^® now being sold.

TransFix^® preserves the profile of the blood sample that exists at the time it is applied. If it is added to a sample that is 24 hours old the profile preserved will be for a 24 hour sample. Therefore, for the best results the blood sample should be stabilised as soon as possible.

A. Yes. However when using TransFix^® with samples collected from leukaemic patients it may be necessary to establish an appropriate volume of reagent to add, which may be different to that quoted in the procedure. Volumes in the region of 0.5-1.0ml per ml of blood may be more appropriate. As a general guide TransFix^® will protect the antigens listed below:

CD2, CD3, CD4, CD5, CD7, CD8, CD10, CS11B, CD13, CD14, CD19, CD20, CD22, CD23, CD33, CD34, CD45, CD79B and HLA-DR

A. Yes, it has been tested on mouse, rat, guinea pig, sheep, horse, pig and green turtle. The volume of TransFix^® required to effectively stabilise 1ml of blood in different species varies considerably. In some species the volume required also varies by breed and type.

The user must determine the optimal dilution required by setting up a concentration curve, starting with 0.05ml per ml of whole blood and going up in 0.05ml steps to 0.4ml. Samples should be analysed before addition of TransFix^® to establish a scatter diagram. The TransFix^® treated samples should then be tested 10 days later. The optimal dilution is the concentration that gives the same scatter diagram as the original after 10 days storage at 4°C.

A. Bulk TransFix^® can be stored at temperatures between 2°C and 24°C. TransFix^® Vacuum Blood Collection Tubes, CSF Storage Tubes and Sample Storage Tubes must be stored at 2°C to 8°C (refrigerated). TransFix^® must NEVER be frozen.

A. Refrigerated at 4°C. TransFix^® treated samples are also stable at temperatures up to 22ºC for up to 7 days and at temperatures between 24°C and 37°C for up to 3 days. (Bergeron et al - Cytometry – 2002) Copies are available as a PDF download from the web site.

A. TransFix^® should not be used beyond the expiry date on the package. When TransFix^® is contaminated it becomes cloudy. Normal appearance is that of a clear pale green / blue liquid.

A. Yes, but it also causes a progressive permeabilisation of the cellular membrane. This means that the intracellular markers will leach out over time. As a general guide intracellular antigen measurement on TransFix^® treated samples is only possible up to 3 days after the addition of TransFix.

A. Samples treated with TransFix^® retain morphology and cell surface expression over time. Shipping and handling of HIV+ samples involved inherent elevated costs and a risk of exposure to the HIV virus. The study showed that HIV+ blood samples showed a 1-log reduction in HIV replication as measured by HIV p24 antigen production. The results indicate that TransFix^® has the ability to cause significant reduction in HIV replication.

Evaluation of TransFix, a commercial whole blood stabilizing reagent. This product reduces HIV replication. Kim et al: Cytometry, Clinical Cytometry (2002) 50: 281

A. Yes, but the user must define the optimal concentration of TransFix^® to use in their particular application.

The user must determine the optimal dilution required by setting up a concentration curve, starting with 0.05ml per ml of whole blood and going up in 0.05ml steps to 0.4ml. Samples should be analysed before addition of TransFix^® to establish a scatter diagram. The TransFix^® treated samples should then be tested 10 days later. The optimal dilution is the concentration that gives the same scatter diagram as the original at 10 days storage.

A. Yes, but the user must define the optimal concentration of TransFix^® to use in their particular application. See above.

A. No, TransFix^® is a preservative that fixates the cells. As a result they cannot be used in functional studies.

A. TransFix^® can be used in conjunction with all commonly used anticoagulants. However we recommend the use of k3EDTA over other anticoagulants.

A. No. Most commonly used red cell lysis buffers are compatible with TransFix. Problems can occur if the lysis buffer is below room temperature when used. The buffer should be allowed to come to room temperature before application. Cal-Lyse works well in association with TransFix^®

A. Yes. A detailed protocol is available on the web site.

A. Yes. A detailed protocol is available on the web site.

A. There is no information available on this application.