An Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL) cell line, designated Black93, was established in culture from a patient who developed acute tumor lysis syndrome (ATLS). Growth inhibition in vitro by dexamethasone (DXM) and the expression of bcl-2 protein (Bcl-2) were investigated in Black93 and 17 other cell lines derived from EBV-negative or -positive BL, pre-B acute lymphoblastic leukemia (ALL), follicular lymphoma (FL), and EBV-positive lymphoblastoid cell lines of normal B cell origin (B-LCL), assuming an inherent susceptibility of Black93 to cell death. The most marked growth inhibition by DXM was observed in Black93, two other BL, two pre-B-ALL and two FL lines. The other cell lines were less sensitive or were resistant. DNA extracted from the Black93 cells treated with DXM showed a ladder of oligo-nucleosomal DNA on electrophoresis. On testing of fixed smears by indirect immunofluorescence, bcl-2 protein (Bcl-2) was undetectable in Black93 and three BL lines but was detected in all the other cell lines at varying intensity. Western blot analysis showed mostly the same results. In the BL lines, the most DXM-sensitive cell lines lacked Bcl-2 expression, and the DXM-resistant cell lines always expressed Bcl-2. While none of the DXM-resistant cell lines lacked Bcl-2 expression, several pre-B or FL lines that expressed [correction of expessed] Bcl-2 were sensitive to DXM. Black93 is the first reported cell line established from a patient with ATLS. The positive sensitivity to DXM and the lack of Bcl-2 expression observed in Black93 are a major characteristic exhibited frequently by BL lines and, probably, by fresh BL cells. These properties may contribute to the precipitation of ATLS.