Detection of malignant B lymphocytes in cerebrospinal fluid by using BIOMED-2 PCR

Abstract

The purpose of this study was to develop a sensitive method for the detection of malignant B lymphocytes in cerebrospinal fluid (CSF) from patients with diffuse large B-cell lymphoma (DLBCL) who were considered as risk of central nervous system (CNS) involvement. Nine CSF samples were collected and then centrifuged. The cell precipitate was lysed directly. The supernatant was used to detect immunoglobulin heavy chain (IgH) gene rearrangement (characteristic changes of malignant B lymphocytes ) by BIOMED-2 PCR. The sensitivity of this method was compared with that of cytology defection and flow cytometry. In addition, through a series of quantity/concentration of tumor cells, the sensitivity differences caused by two sample handling methods (direct cell lysis vs traditional DNA extraction) were analyzed, and the sensitivity of direct cell lysis combined with BIOMED-2 PCR was evaluated. The results showed that the positive clonality of IgH gene rearrangement were detected by BIOMED-2 PCR in 5 cases, but the positive were detected by cytology defection/flow cytometry only in 2 cases, which indicated that the BIOMED-2 PCR assay gives a better yield. In addition, when combined with BIOMED-2 PCR, direct cell lysis produced sensitivity much higher than DNA extraction. The former can enable clonality detection from a minimum of 0.1%/20 tumor cells. It is concluded the method of direct cell lysis combined with BIOMED-2 PCR is sensitive and suitable for paucicellular CSF detection. It may aid the diagnosis of CNS involvement in patients with DLBCL.