Establishment and characterization of a human T-lymphocyte cell line immortalized by SV40 and with abnormal expression of TCR/CD3

Human lymphocytes derived from the peripheral blood of a healthy woman were transfected with a plasmid carrying the simian virus 40 (SV40) large T ant igen. The successfully transformed cells contained SV40 large T DNA and wer e negative for Epstein-Barr virus (EBV) and human T-cell leukaemia virus (H TLV)-1 genomes. The immortalized cell line was assigned to the T-lymphocyte lineage on the basis of morphological, immunological and cytochemical crit eria, While the cells expressed CD1a and CD4 at the cell surface, the CD3 c omplex was solely intracytoplasmic. Immunoprecipitation studies indicated t hat these cells lacked T-cell receptor (TCR) alpha-chains but not beta-chai ns. They were negative for activation markers such as CD25, CD69 and major histocompatibility (MHC) class II molecules. In addition, the transformed c ells exhibited a complete growth independency towards interleukin-2 (IL-2), However, after phorbol ester stimulation, CD25 and CD69 markers were expre ssed and IL-2 was secreted. This new human immortalized T-lymphocytic cell line, which is cell-surface TCR/CD3-negative, may be useful as an in vitro model for studying TCR/CD3 assembly, expression and signal transduction.