B cell stimulating activity of metallothionein in vitro

The effect of metallothionein (MT) on lymphocytes was studied in vitro. Rab bit MT induced the proliferative responses of mouse splenocytes at concentr ations of 1-25 mu g/ml. MT synergistically enhanced Con A- or LPS-induced p roliferative response of splenocytes. A similar effect was also observed fo r rabbit splenocytes at a similar concentration. Free heavy metals such as Cd and Zn only weakly stimulated splenocytes. 2-mercaptoethanol (2-Me) abro gated the effect of MT, suggesting that thiols in MT play an: important rol e for splenocyte response. MT stimulated splenocytes from MT-knockout mice as well as those from normal control mouse. The responder cells for MT stim ulation were B cells and MT also induced B cell differentiation to produce Ig. MT induced the calcium influx-of B cells, but not T cells. These result s indicate that MT has a potent immunomodulating activity, especially on B cells. (C) 2000 International Society for Immunopharmacology. Published by Elsevier Science Ltd. All rights reserved.