Comparative characterization of lymphotoxin transcripts from human B- and T-cell lines, peripheral lymphocytes, and normal tissues

Membrane lymphotoxin (LT) is a heterotrimer LT alpha (1)beta (2), and its p roduction depends on two genes. Northern blotting was employed in studying their transcription in human B- and T-lymphoma cell lines and in peripheral blood lymphocytes before and after induction with phorbol myristate acetat e (PMA). Transcription of either gene proved to be similarly regulated in s everal cell lines and in blood lymphocytes. Activation of the LT alpha gene was associated with induction of transcription factor NF-kappaB (p50/p65) upon cell treatment with PMA. On evidence of RT-PCR, two transcripts of the LTP gene were present in equimolar amounts in all lymphoid cells. A produc t of alternative splicing contained an open reading frame coding for the cy toplasmic portion of LTP.