Analysis of the T cell activation signaling pathway during ELF magnetic field exposure, p56 lck and [Ca 2+] i-measurements

Abstract

Extremely low frequency magnetic fields (MF) have been shown to alter the intracellular calcium concentration ([Ca 2+] i) in the human leukemic T cell line Jurkat. Real-time [Ca 2+] i oscillations were measured in different mutant Jurkat clones upon exposure to 50 Hz, 0.15 mT. A clone not expressing the T cell receptor α and β chains showed a reduced calcium response to MF compared to wild-type Jurkat (E6-1). A p56 lck mutant clone showed a low response, which was restored when Lck was reconstituted, giving a response similar to that seen in E6-1 cells. The tyrosine phosphorylation intensity of immunoprecipitated Lck in E6-1 cells was higher in MF than sham-exposed cells. In addition, both cholera toxin (CTX) and the protein tyrosine kinase inhibitor genistein completely blocked the [Ca 2+] i increase in Jurkat E6-1 cells upon MF exposure. Thus, MF affects the early events in a signalling pathway from the T cell receptor, although not exactly mimicking an anti-CD3-initiated [Ca 2+] i response.