IMMUNOGLOBULIN SYNTHESIS IN BURKITT'S LYMPHOMA

Abstract

American Burkitt's lymphoma has been identified as a monoclonal IgM (Kappa or Lamba chain) lymphoprolipherative disorder. The nature of immunoglobulin synthesis in culture of tumor derived from 3 such patients (ages 5, 6, and 15 years) was investigated. Tissue with cytologic and morophilogic Burkitt's criteria included mediastinal node, abdominal node and marrow. Cells were cultured as 1 × 10⁶ cells/ml in leucine-difficient Eagle's media containing 10% fetal calf serum and 5 uC ³H-leucine in 5% CO₂ at 37°C for 72 hours. Ig's were measured by solid phase radioimmunoassay. Specific anti-Fab and anti-IgG, M, and A, following elution from insoluable immunoabsorhants, were convalently linked to bromacetyl cellulose (BAC) and specificity was established on acrylamide gels. Synthesis was determined as degradation (DPM)/10⁶ cells: total protein - 1800 (640-2570), Ig-120 (20-280). Molecular weight of the Ig was consistant with IgM and verified with BAC-anti-IgM. Neither IgG nor IgA were synthesized. The % of newly synthesized protein as IgM ranged from 2.5-12.5%. Total protein (TP) and total Ig synthesized from normal lymphocytes in culture averaged 3100 and 290 DPM/106 cells, respectively (%TP as Ig-9%: IgG-5.5%. IgM-3%. IgA-1.5%). With this method, Ig quantitation clearly identified IgM as the sole Ig synthesized by this tumor. The patients were treated alike (prednisone, cyclophosphamide and vincristine initially). The longest survival to date has occurred in the patient with the highest level of IgM synthesis.