Blood Controls

Routine haematological testing requires the use of reference material during machine set up such that validation prior to analysis of patient samples can be performed. Many also require repeat use of reference controls throughout the running period of the machine, ensuring sample processing, equipment and operators are all performing optimally, thereby providing quality assurance.


In Flow Cytometry however, it has not been the norm to use reference material since it has not previously been possible to stabilise samples for use as a reference. Using proprietary blood stabilisation technology, Cytomark can now produce stabilised human whole blood with both normal and low CD4 counts for use as blood controls. The stabilisation process is robust resulting in controls that are stable for up to 90 days from the date of manufacture when stored at 2 - 8°C, and an open vial stability of 1 month.


The stabilised controls allow gating, and forward and side scatter flow cytometric effects to be determined during machine set up and before and during analysis of patient samples.


The ISO standard entitled ‘ISO 15189: Medical laboratories - Particular requirements for quality and competence’, refers to the requirement for reference samples during flow cytometer set up and running. Cytomark's Stabilised Human Whole Blood and CD4 Low and Normal Controls provide suitable reference samples for this purpose.


Key Benefits of Cytomark's Blood Controls:


Verification of monoclonal antibodies and flow cytometry reagents

Validation of flow cytometer performance

Validation of operator technique

Verification of red blood cell lysis


Blood Controls Available:


Stabilised Human Whole Blood

The Stabilised Human Whole Blood control is supplied with a QC certificate detailing the expected count and range for T cells (CD3+), T helper cells (CD3+CD4+), T suppressor cells (CD3+CD8+), NK cells (CD56+)and B cells (CD19+).


CD4 Low and Normal Blood Controls

The CD4 Normal Blood Control contains CD4+ T cells in the normal range (410-1590 cells/µl) and the CD4 Low Blood Control contains CD4+ T cells in a low range (200-300 cells/µl). These controls can be purchased separately or as a pair.


If you would like to be alerted when a new batch of Blood Controls are released, please This email address is being protected from spambots. You need JavaScript enabled to view it..

TransFix is a CE marked solution that preserves leucocytes and leucocytic antigens in human peripheral blood for flow cytometric analysis. TransFix is used to extend the timeframe for sample analysis, providing flexibility in testing. Samples treated with TransFix are stabilised for up to 10 days when stored at 2-25°C, and for 4 days at temperatures between 25-37°C. TransFix is widely used for immunophenotyping purposes in hospitals and reference laboratories, as well as academic research institutions, pharmaceutical & biotechnology companies. TransFix can also be used with other cellular samples for research applications.

Cytomark's Blood Controls are reference samples that can be used during the set up and running of flow cytometers to provide quality assurance that equipment & processing procedures are performing optimally. These controls are produced from stabilised human whole blood with both normal and low CD4 counts. Each reference is provided with a QC certificate detailing the expected count and range for T cells (CD3+), T helper cells (CD3+CD4+), T suppressor cells (CD3+CD8+), NK cells (CD56+)and B cells (CD19+).

TransFix - a Cellular Antigen Stabilisation Reagent:

The intended use of TransFix is for immunophenotyping; when added to samples at the point of collection, TransFix immediately stabilises leukocytes for up to 10 days, providing flexibility in analysis. For human whole blood samples, Cytomark routinely QC test that the immunophenotypic profile is maintained for 10 days for cells with markers: CD3, CD4, CD8, CD16, CD19, CD45, and CD56. TransFix can also be used for monitoring CD4 and CD8 T-cell subsets of human immunodeficiency virus (HIV)-infected individuals using Flow Cytometry.

Stabilisation of cerebrospinal fluid is also possible using Cytomark's TransFix/EDTA CSF Sample Storage Tubes, which have been developed in collaboration with oncologists specifically for this purpose. Independent research has also been published on the stabilisation of bone marrow samples using the TransFix reagent.

Features and Benefits of TransFix:

Stabilises cell surface antigens for a minimum of 10 days at 2-25°C and for 4 days at 37°C
Easy to use, just add TransFix and mix by inversion
Ensures sample integrity during transportation between clinical sites
Eliminates the need for weekend and evening work
Reduces the impact of unexpected machine breakdown or staff shortages
Allows for repeat testing of samples without the need for patient recall and repeat phlebotomy
Greater efficiency in testing - allows for batching of samples prior to testing
Reduction in costs associated with the above advantages

Comparison of the leucocytic immunophenotype in normal human whole blood analysed immediately after collection, untreated after 11 days and stabilised with TransFix for 11 days:


Fig. 1 Diagrams A) and B) are flow cytometry density dot plots that demonstrate the normal leucocytic immunophenotype in a fresh sample of human whole blood. Granulocyte, monocyte and lymphocyte populations are all distinct (A) as are T Cells, NK Cells and B Cells (B). Diagrams C) and D) demonstrate the leucocytic immunophenotype in the same sample of human whole blood after 11 days of storage. leucocyte subsets, particularly monocytes are less distinct (C) and B Cells and NK Cells cannot be easily identified (D). Diagrams E) and F) demonstrate the leucocytic immunophenotype in the same sample of human whole blood after treatment with TransFix and storage for 11 days. All leucocyte subsets, including monocytes, B Cells and NK Cells can be clearly identified (E & F).

These images are taken from Cytomark's in-house Quality Control Tests (Cytomark, Buckingham, UK)


TransFix Applications

TransFix can also be used for a number of applications. Find out more about these applications on the Cytomark website by clicking on the links below:


Human Blood Stabilisation - Clinical Applications

Human Blood Stablisation - Research Applications

Cerebrospinal Fluid Stabilisation

Bone Marrow Stabilisation

Animal Blood Stabilisation

Immunostaining of Circulating Tumour Cells



          Cytomark are dedicated to the development of cell stabilisation reagents for use in flow cytometry. Based in Buckingham, UK, Cytomark specialise in the development of two key product areas: TransFix® and Blood Controls. Cytomark manufacture TransFix® and Blood Controls for scientists all over the world. We are committed to helping organisations reduce the pressure associated with the analysis of fresh samples, and also provide quality assurance that their equipment and sample processing procedures are performing optimally.


ISO 13485 Accreditation

ISO 13485:2003

Caltag Medsystems Ltd. are certified to the ISO 13485:2003 standard.

Globally recognised, the ISO 13485 standard defines the quality management system requirements for manufacture of medical devices. For Caltag Medsystems, ISO 13485 accreditation incorporates the "manufacture and supply of cellular stabilisation reagents for research and in vitro diagnostic use".

Caltag Medsystems, under the Cytomark brand, already manufactures a number of products for the medical sector. Maintaining the ISO 13485 certification demonstrates that our quality credentials have been proven through independent verification.




        Abnova is the world's largest antibody manufacturer. We have the capacity of generating 300 mouse monoclonal antibodies and 200 rabbit polyclonal antibodies per month. Rather than the traditional method of antibody production, Abnova is taking a genomic/proteomic approach for the antibody development. Our goal is to have at least one antibody to every human expressed gene in human genome. We manufacture all our products, recombinant proteins and antibodies in our state-of-the-art production and SPF animal facilities. We also have multiple clones for the monoclonal antibody, and their access is available to partners and collaborators from the academic institutions and industry.


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Buffers, Reagents & Chemicals

          G-Biosciences offers quality reagents for a wide variety of research applications. These ready to use solutions provide a convenient, reliable and cost effective supply of high quality reagents. Each reagent lot undergoes strict quality control to ensure expected performance. A large selection of chemicals are available and include PBS, Triton-X, Molecular Grade Water, and our Molecular Biology Universal Kit.