Occupational asthma from nickel sensitivity: I. Human serum albumin in the antigenic determinant

Occupational asthma from nickel sensitivity was confirmed in a male worker (SB) by allergy skin tests and inhalational challenge. In an ammonium sulphate coprecipitation test 63Ni was selectively precipitated from SB plasma indicating antibody with nickel related specificity. Preincubation of 63Ni with human serum albumin (HSA) increased the specificity of the coprecipitation test. Blocking experiments with nickel and copper(II) salts effectively inhibited the binding of 63Ni to antibody of SB plasma but did not affect control tests or that for antibodies to an unrelated antigen, ampicillin. Co2+ slightly inhibited the binding of 63Ni, while Zn2+ and Mn2+ failed to inhibit. This deactivation pattern corresponds to the known sequence of binding of these metals to the primary copper binding site of HSA. It is concluded that the antigenic determinant depends on the combination of Ni2+ with HSA at this specific copper/nickel plasma transport site.