Letter

Assessment of monocytic HLA-DR expression in ICU patients: analytical issues for multicentric flow cytometry studies

Guillaume Monneret1*, Fabienne Venet1, Christian Meisel2 and Joerg C Schefold3

Author Affiliations

1 Cellular Immunology Laboratory, Hôpital E. Herriot, Hospices Civils de Lyon, Pavillon E, 5 place d'Arsonval, 69437 Lyon Cedex 03, France

2 Department of Medical Immunology, Charité University Medicine, Campus Mitte, CharitéPlatz 1, Berlin 10117, Germany

3 Charite University Medicine, Department of Nephrology and Intensive Care Medicine, Augustenburger Platz 1, 13353 Berlin, Germany

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Critical Care 2010, 14:432 doi:10.1186/cc9184


See related research by Gogos et al., http://ccforum.com/content/14/3/R96, related commentary by Cavaillon and Adib-Conquy, http://ccforum.com/content/14/3/167 and related letter by López-Collazo et al., http://ccforum.com/content/14/4/435


The electronic version of this article is the complete one and can be found online at: http://ccforum.com/content/14/4/432


Published:27 July 2010

© 2010 BioMed Central Ltd

Letter

We read with interest the recent report by Gogos and colleagues [1]. While the rationale for their study is excellent, we would like to comment on technical issues that may have influenced the results.

As stated, a time limit of 8 hours between sample drawing and staining at a central laboratory was specified [1]. Unfortunately, information regarding transport conditions is missing (average time, temperature). This seems important since monocytic HLA-DR expression (mHLA-DR) increases artificially over time [2,3]. Consequently, recommendations suggest that sample staining for mHLA-DR should occur within 4 hours [2,3]. Although the authors aimed to address the effect of transportation, they inappropriately used samples presenting with already near-maximal mHLA-DR values (> 90%) before storage. We therefore assume that mHLA-DR results may be falsely elevated due to prolonged transportation times. Furthermore, mHLA-DR modulation during sepsis takes days and consecutive measurements are required [4]. Assessment of one early sample (within the first 24 hours) is probably inappropriate to investigate the impact of infection on mHLA-DR. Similarly, apoptosis staining should not be performed after 8 hours and experts' recommendations highlight the need for dedicated protocols on fresh cells [5].

We are convinced that successful future trials in sepsis will rely on our capacity to accurately assess immune responses. In that sense, flow cytometry multicentric clinical studies are essential. Such trials should be performed in standardized environments in accordance with specific (pre)analytical requirements. Otherwise, results might be misinterpreted and may impede promising new avenues in future care of septic patients.

Abbreviations

ICU: intensive care unit; mHLA-DR: monocytic human leukocyte antigen DR-1.

Competing interests

The authors declare that they have no competing interests.

References

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