Multicentre evaluation of stable reference whole blood for enumeration of lymphocyte subsets by flow cytometry.

BACKGROUND: Clinical indications for lymphocyte subset enumeration by flow cytometry include monitoring of disease progression and timing of therapeutic intervention in infection with human immunodeficiency virus. Until recently international standardisation has not been possible due to a lack of suitable stable reference material. METHODS: This study consisted of two trials of a stabilised whole blood preparation. Eleven participants were sent two standard protocols for staining plus gating strategy and asked to report absolute counts for lymphocyte subsets. RESULTS: No significant difference was detected between the two methods when results from the two assays and all partners were pooled. Significant differences in results from the different partners were observed. However, representative mean counts were obtained for geometric means, geometric coefficient of variation, and 95% confidence interval for CD3 910 cells/mul, 9%, and 888 to 933, respectively), CD4 (495 cells/mul, 12%, and 483 to 507), and CD8 (408 cells/mul, 13%, and 393 to 422). CONCLUSION: We have introduced a stabilised blood preparation and a well-characterized biological standard. The availability of this reference material greatly simplifies the validation of new techniques for CD4(+) T-cell enumeration and the expansion of external quality assurance programmes for clinical laboratories, including those that operate in resource-restricted environments. (c) 2005 Wiley-Liss, Inc.

Immunophenotyping of plasma cells in multiple myeloma.

Multiparametric immunophenotyping of multiple myeloma (MM) and other plasma cell (PC) dyscrasias represents an attractive approach not only for research purposes but also in clinical practice. Based on well-established antigenic patterns, discrimination between myelomatous and normal PCs can be easily achieved in various types of samples, and this can be particularly valuable for the differential diagnosis between MGUS and MM and for monitoring residual disease in the latter. In addition, immunophenotyping may be an alternative and more reproducible method than morphology for evaluating PC infiltration, as well as for specifically analyzing DNA content and the cell-cycle distribution of different subsets of PCs. Despite the widespread use, standardization of methods and protocols still remains a challenge. In this chapter, we describe in detail the protocols and precise instructions for specimen collection, sample preparation, together with the methods for staining PCs and flow cytometry, data acquisition, and data analysis, including the more recent developments in the field. We highlight the most frequent limitations, and provide troubleshooting and practical recommendations that could help to solve them. The goal of this chapter is to emphasize the relevance of methodological issues in order to obtain reproducible and high-quality results regarding the phenotypic analysis of PCs.