Induction of a 70-kDa protein in human lymphocytes exposed to inorganic heavy metals and toxic organic compounds.

Human peripheral blood lymphocytes synthesize a 70-kDa protein (p70) distinct from metallothionein (MT), in response to several inorganic heavy metals. Although Cd and Zn induce both p70 and MTs, Co induces only p70. On the other hand, Cu, Hg, Ni and Ag, which are the inducers of MTs, can not induce p70. This protein is indistinguishable in electrophoretic mobility from the 70-kDa heat shock protein, which is induced by incubation of lymphocytes at 42-45 degrees C. Several environmental pollutants other than the inorganic heavy metals, including organic tin compounds and organic phosphorus compounds, were also found to induce p70. The responsiveness to a variety of environmental stimuli suggests the involvement of p70 in the basic cellular defense mechanism.