The antigen-binding capacity of serum IgG. An immunosorbent method applied to subtilisin as antigen

A method for estimating the antigen-binding capacity of serum IgG is presented. A Sepharose anti-human IgG immunosorbent is incubated with test serum and washed. The antigen-binding capacity of the bound specific IgG is determined by incubation with purified, inactivated 125I-subtilisin. The method was applied tp the sera of workers in the detergent industry exposed to enzymatic preparations from Bacillus subtilis. The sera of 33 out of 69 workers bound a detectable amount of subtilisin, the detection limit ranging from 8--34 ng/ml in different assays. The amount of antigen bound ranged from 42--9380 ng/ml. IgG to subtilisin was not detected in the sera of 61 subjects with no known exposure to subtilisin and who were not factory workers.