Characteristics of new cell lines derived from Burkitt lymphomas

Thirty‐five cell lines were established from 47 Burkitt lymphoma biopsies. In different biopsies the modal cell size was found to vary and the tumor was often built up by larger cells if the patients received chemotherapy. In all cases the predominant cell size shifted towards larger values during cultivation. All cells in three biopsies from one patient and in the culture lines derived showed surface reactivity with anti‐IgM and antikappa light chain reagents. This trait was maintained in all three lines for about 21 weeks but was lost thereafter. A fourth biopsy—taken after the patient had been treated with cytosine arabinoside—did not have this immunoglobulin reactivity. Chromosomal analysis revealed that one of the IgM reactive lines had 46 as stemline number and normal diploid karyotype, while the nonreactive line had 47 as stemline number with an extra C chromosome in addition to the normal male karyotype. One or two C chromosomes, corresponding in size with pair 10 were formed as markers with subterminal constriction on their long arms. The unusual cellular trait—IgM specificity—being present on both the biopsy and its derived cell line, indicates the representativeness of the culture line for the in‐vivo tumor in this case.