THE HEAVY METAL MERCURY MODULATES p-ERK1/2 IN ACTIVATED B-CELLS (86.7)

Abstract

Abstract The heavy metal mercury (Hg) is known to have immunomodulatory properties affecting lymphocyte signal transduction, death receptor signaling and autoimmunity. We tested the hypothesis that Hg exposure modulates B-cell activation in response to BCR stimulation. To test this hypothesis; WEHI-231 immature B-cells, were stimulated with Goat-anti-IgM in the presence or absence of 5 μM HgCl2. We found a significant reduction in p-ERK1/2 in the presence of Hg by Western blot. However, it is unclear whether the reduction of BCR dependent pERK is a consequence of Hg modulating the amount of p-ERK1/2 in each cell, or whether Hg is reducing the number of responding cells in the population. Single cell proteomics were employed to address whether pERK1/2 is modulated on a per-cell-basis using a ERK phosphospecific fluorochrome labeled antibody. We found nearly 80% of the WEHI cells, possess pERK1/2 by 5 minutes after stimulation. Interestingly, pre-incubation with HgCl2 causes a 25% decrease in the percentage of responding cells after IgM stimulation. Moreover, the MFI of pERK1/2, is reduced by more than 30% following exposure to HgCl2. Additional studies in primary mouse B-cells have found Hg also modulates phosphorylation of the proximal BCR kinase Syk. Taken together these data suggest Hg modulates BCR signal strength which may have profound implications for establishment of self-tolerance within the B-cell repertoire.