Cytomark  >  About Us
Stabilise antigens for up to 14 days

About Us

Hello, and thank you for visiting our website.

Here at Cytomark (a division of Caltag Medsystems Ltd.), we are dedicated to the development of cell stabilisation reagents for use in flow cytometry. Based in Buckingham, we manufacture TransFix®, TransFix-related products 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.

Our customer service team and technical specialists offer comprehensive support and look forward to working with you.

Our History

TransFix® was developed by medical scientists from UK NEQAS out of the requirement to produce stabilised blood samples that could be used in External Quality Assurance programs for flow cytometry.

TransFix® has been in circulation amongst the research world since 1999. In 2005, the NHS licensed TransFix® to Cytomark, making it readily available to the clinical and scientific world.

The launch of Cytomark coincided with Caltag Medsystems (the parent company of Cytomark) relocating to occupy facilities in Botolph Claydon, Buckinghamshire, gaining access to GMP laboratories.

In 2009, after outgrowing the facilities in Botolph Claydon, we relocated to the Whiteleaf Business Centre in Buckingham. Our facilities here include manufacturing and product development laboratories with an increased capacity to further develop and manufacture cell stabilisation products such as TransFix®.


TransFix® is a CE marked solution for IVD use that prevents cellular degradation in human peripheral blood for analytical testing purposes. Leucocytes and leucocytic antigens are stabilised for up to 14 days at sample storage temperatures between 2-8°C, and for 4 days at temperatures between 25-37°C . TransFix® is also used to stabilise CSF and bone marrow prior to flow cytometric analysis. As a result, samples treated with TransFix® can be analysed at a more convenient time for the operator.

For a list of countries where TransFix® is registered as an IVD product, please click here.

Our products are widely used in hospitals, reference laboratories, academic research institutions, pharmaceutical and biotechnology companies, and government agencies.

TransFix® Applications

Manufacturing & Quality Control





Blood Controls

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. Our Stabilised Human Whole Blood and CD4 Low and Normal Controls provide suitable reference samples for this purpose. 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 have an open vial stability of 1 month.

Please contact us for further information.

Blood Controls Available:

Manufacturing & Quality Control





Company Certification

ISO 13485:2016

Caltag Medsystems Ltd. are certified to the ISO 13485:2016 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 "development and manufacture of cellular stabilisation reagents for research and in vitro diagnostic use".

Caltag Medsystems Ltd. manufactures TransFix® products on behalf of Cytomark Ltd. Maintaining the ISO 13485 certification demonstrates that our quality credentials have been proven through independent verification.

Regulatory Statement

Our Customer Service and Technical Support Teams

We try our very best to provide the most comprehensive level of support to our customers.

Our priority is customer satisfaction. Whether it's an ordering enquiry, a technical question or a finance matter, we are here to help. Whatever your query, please get in touch:

Tel: +44 (0) 1280 827460

Meet Our Customer Service Team









Meet Our Technical Support Team











If you have any suggestions, problems or complaints regarding our products or services please let us know. Your feedback is important to us.

The Management Team




Company Information

Cytomark is a Division of Caltag Medsystems Ltd.

Cytomark Ltd. is registered in the UK, No. 11863469
Registered Office: Whiteleaf Business Centre, 11 Little Balmer, Buckingham, MK18 1TF, UK
VAT Reg. No. GB 317 0847 08

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