Revista de Bioanálise e Biomedicina

Enhanced Content of IgG in Burkitt’s Lymphoma Cells after Treatment with the Topoisomerase II Inhibitor, Lucanthone

Abstract

Robert Bases, Rukmani Lekhraj, Xudong Tang, Jinghang Zhang, Zhi Duan, Jennifer T Aguilan and Edward Nieves

Burkitt’s lymphoma cells (CRL-1647) which had survived treatment with lucanthone contained 3.6 fold more IgG than untreated cells, although most of the cellular immunoglobulins were still IgM. DNA activation induced cytidine deaminase (AID) was increased 5 fold in these surviving cells, consistent with active Class Switch Recombination (CSR).

Progeny of the small fraction of cells which had survived 20 h exposure to 8 μM lucanthone before rescue were cloned. 1.5 × 108 cloned cells contained ~1 μg of cytidine DNA deaminase, as determined from affinity column isolation of the enzyme, assayed by digestion of a 30 nt 32P labeled specific DNA substrate. Before lucanthone treatment, little AID could be detected. After the second treatment, a six fold increase in AID was found. In confirmation, Western blot determinations of AID from lysates of lucanthone treated cells showed 5 fold increased AID content. These results suggest that lucanthone led to increased IgG content of surviving cells, consistent with their increased AID activity. The surviving cells were also more resistant to the standard lucanthone treatment, as determined in clonogenic assays.

IgG could not be detected in the cell membranes of CRL cells before or after lucanthone by immunostaining and flow cytometry, but both cell types secreted 80 kDa and 25 kDa immunorelated protein.

Lucanthone, formerly used to safely to treat hundreds of thousands of schistosomiasis patients, might be considered as a means to promote IgG synthesis in macroglobulinemia patients.