Dried Blood Spots Detect Clonal B-Cell Populations

The reliability of lymphoma diagnoses is strikingly different between developed and developing countries due to lack of access to advanced techniques.

Molecular methods are important tools for diagnosis and monitoring of many lymphoproliferative disorders, and new application of dried blood spots (DBS) for detecting clonal B-cell populations in peripheral blood (PB) has been proposed.

Scientists at the University of Padua (Italy) obtained blood samples from six patients with B-cell chronic lymphocytic leukemia (B-CLL) and five consenting healthy volunteer donors. Dried blood spot samples from African children with non-Hodgkin's lymphoma (NHL) were also analyzed.

Genomic DNA was isolated with the automated MagNA Pure Compact instrument (Roche Applied Science, Indianapolis, IN, USA) The extracted DNA samples were tested for B-cell immunoglobulin heavy chain (IGH) clonality with the IGH gene clonality assay (Invivoscribe Technologies; San Diego, CA, USA), containing BIOMED-2 primers, positive and negative controls.

The Namalwa B-cell line was used to establish that the assay was sensitive enough to detect 200 clonal cells in the analyzed sample. Very similar clonal results were obtained between DNA from DBS and fresh whole blood from patients with B-cell chronic lymphocytic leukemia. B-cell clonality can also be detected in DBS from African children with Epstein-Barr Virus (EBV)-associated diseases.

DBS cards are a feasible alternative for diagnosing and monitoring various diseases in the developing world. DBS sampling was also suitable to verify the presence of B-cell clonal populations circulating in the blood by immunoglobulin gene rearrangement analysis, with a view to offering molecular evaluation to the diagnosis and monitoring of lymphoproliferative diseases in resource-limited settings.

A diagnosis of leukemia is not usually problematic as immunophenotyping and cytogenetic analysis and histochemical staining can establish diagnosis in virtually all leukemia cases. However, a diagnosis of leukemia may sometimes be more complicated, and molecular clonality evaluation is thought to produce valuable additional information. DBS cards may be useful tools when the molecular analyses complementary to histomorphological/immunophenotypic evaluation are not available. The study was published in the October 2013 issue of the journal Leukemia Research.

Related Links:
University of Padua
Roche Applied Science
Invivoscribe Technologies