ELF magnetic fields initiate protein tyrosine phosphorylation of the T cell receptor complex

The human T cell line Jurkat registers a sinusoidal extremely low frequency (ELF), 0.10 mT magnetic fields (MFs) at the level of the plasma membrane. In this study, the protein tyrosine phosphorylation (PY) of two membrane-as sociated proteins in Jurkat cells were examined following a short-term MFs exposure, the zeta chains and the Src kinases p56(lck). These proteins are interesting to study since the earliest biochemical event upon T cell recep tor (TcR) activation is PY of the zeta chains. These signalling chains in t he TcR complex was assessed using Western blotting and the activation of th e p56(lck) kinase was analysed by in vitro kinase assay. The MFs exposure o f Jurkat for 5 min activated p56(lck) and resulted in PY of zeta. These fin dings are in line with earlier reports on how MFs exposure affects signal t ransduction in Jurkat. (C) 2000 Elsevier Science S.A. All rights reserved.