The EB1 cell line was isolated by M.A. Epstein and Y.M. Barr in 1963 from biopsy fragments and cell clumps of a lymphoma. These were seeded into Insulin bottles in Eagles basal medium with 10% human serum and fed by medium addition. The cells grew as free-floating singel individuals or doublets with a mean doubling time of about 48 hrs and were identified as altered lymphoblasts on the basis of growth and uniform morphology.