Reproducibility Studies for Experimental Epitope Detection in Macrophages (EDIM)

Introduction: We have recently described epitope detection in macrophages (EDIM) by flow cytometry. This is a promising tool for the diagnosis and follow-up of malignancies. However, biological and technical validation is warranted before clinical applicability can be explored.

Methods: The pre-analytic and analytic phases were investigated. Five different aspects were assessed: blood sample stability, intra-individual variability in healthy persons, intra-assay variation, inter-assay variation and assay transferability. The post-analytic phase was already partly standardized and described in an earlier study.

Results: The outcomes in the pre-analytic phase showed that samples are stable for 24h after venipuncture. Biological variation over time was similar to that of serum tumor marker assays; each patient has a baseline value. Intra-assay variation showed good reproducibility, while inter-assay variation showed reproducibility similar to that of to established serum tumor marker assays. Furthermore, the assay showed excellent transferability between analyzers.

Conclusion: Under optimal analytic conditions the EDIM method is technically stable, reproducible and transferable. Biological variation over time needs further assessment in future work.