Comparison of cobalt and chromium binding to blood elements

Macromolecular binding of metals is thought to be a prerequisite for induction of metal sensitivity. In this study, the binding of cobalt(II) to blood components was investigated. Incubation of 60Co with blood yielded a mean erythrocyte binding of 10.3 X 10(7) Co atoms/cell. Incubation of the metal with serum resulted in binding of 8.3 X 10(-9) mol Co/mg protein. A comparison was made with analogous binding of chromium(III), a metal recognized for its sensitizing potency. Binding of chromium to proteins and blood cells was 20-fold higher than that obtained with cobalt. With both metals, binding to serum proteins was non-specific. The greater binding by chromium, when compared with cobalt, is consistent with the greater sensitizing ability of this metal.