TransFix^® - Human Blood Stabilisation

Immune Monitoring of HIV/AIDS

Monitoring CD4 and CD8 T-cell subsets of human immunodeciency virus (HIV)-infected individuals is performed routinely by flow cytometry. It is the most commonly used method for monitoring the immune status of HIV-infected individuals. Ordinarily, specimens must be processed within 36 hours to obtain reliable CD4+ T-cell absolute counts.

Blood treated with TransFix^® however, remains stable for a minimum of 10 days when stored at 2-22°C and for 4 days at 37°C. (1). TransFix^® stabilises cell surface antigens, allowing transport back to a laboratory without deterioration. This is particularly important in countries where the transport infrastructure is poor and unreliable.

TransFix^® is also a highly effective anti-viral agent that results in a reduction in HIV replication as measured by HIV p24 antigen production (2). However, samples must still be handled with universal precaution protocols.

Immunophenotyping

Subsets of lymphocytes can be distinguished on the basis of cell surface antigens using flow cytometry. Quantitative and qualitative changes in lymphocyte subsets are used to identify and monitor immunological diseases. TransFix^® is validated using the BD MultiTest™/TruCOUNT tube technology with the Lyse/No Wash system. Cell surface antigens shown to be stable after blood has been treated with TransFix^® and stored for 10 days at 2-8°C include CD3, CD4, CD8, CD45. This information is specified on our Certificates of Analysis and can be viewed at www.cytomark.co.uk/downloads. The wide range of antibody clones and conjugates available make it essential that end-users validate their reagents with TransFix^®.

A) Control Day 0 / B) Transfix Day 0

C) Control Day 10 / D) Transfix Day 10

The above graphs (A-D) show staining examples with CD3 FITC and CD8 PE antibodies (gated on CD45). Graph D shows that TransFix^®-treated blood retains the flow cytometric staining profile of CD3+ cells after 10 days of storage, compared to the control blood (graph C).

Sample preparation for flow cytometry:

1. Administer TransFix to the human blood sample at a ratio of 0.2ml TransFix or TransFix/EDTA per 1ml human blood.
2. Mix by inversion 5-10 times.
3. Store at 2 - 8°C for up to 10 days.
4. Allow the sample to return to room temperature prior to flow cytometric analysis. Also ensure that cells are thoroughly resuspended by inverting the vial 30x.
5. Analyse on flow cytometer.

TransFix^® Vacuum Blood Collection Tubes

TransFix^® Sample Storage Tubes

TransFix^® Bulk

Other formats of TransFix^® are available - click here.

Reference
(1) Bergaron, M. et al., (2002), Evaluation of stabilised blood cell products as candidate preparations for quality assessment programs for CD4 T-cell counting. Cytometry, 50:86–91
(2) Kim, J. et al., (2002), Evaluation of TransFix^®, a commercial whole blood stabilizing reagent. This product reduces HIV replication. Cytometry, 50: 281