CD45 phosphatase in Jurkat cells is necessary for response to applied ELF magnetic fields

Abstract

Oscillations of free intracellular calcium [Ca²⁺]_i were seen in individual Jurkat cells as response to a 50 Hz, 0.15 mT magnetic field (MF). In contrast, a CD45‐deficient Jurkat cell line was unable to respond to MF stimulation. The phosphatase activity of CD45 has been implicated to regulate p56 ^lck tyrosine kinase activity by removing an inhibitory phosphate. By using Jurkat cells that expressed a chimeric molecule, comprising the cytoplasmic phosphatase domain of CD45, the MF induced calcium response was restored. This showed the necessity for an intact signal transduction pathway leading to a calcium increase as a result of stimulation of cells by MF. Thus, our data suggest that the target for the applied MF are molecules involved in early events in the signalling pathway from the T cell antigen receptor.