Figure 2.

Confirmation of the ELISA assay by immunoblotting of recombinant soluble liver antigen/liver pancreas (SLA/LP) antigen. Reactivity of patient sera (1:200) to recombinant SLA/LP antigen was tested by western blotting. Results of immunoblotting were comparable with those in the ELISA assay with recombinant SLA/LP antigen. Shown are the reactivities in western blotting of representative sera that were either positive in the ELISA assay (lanes 1 and 2), negative (lanes 3 and 4), or borderline positive (lanes 5 and 6). The corresponding reactivity in the ELISA assay of the serum shown in lane 1 was above 200 relative units (RU)/ml; that of serum in lane 2 was 95 RU/ml; serum in lane 3 was below 2 RU/ml; serum in lane 4 was 2 RU/ml; serum in lane 5 was 22 RU/ml (remaining positive in western blotting); and serum in lane 6 was 16.25 RU/ml (negative by western blotting). As controls we used: a positive standard serum (lane 7; above 200 RU/ml); a monoclonal antibody to the recombinant SLA/LP protein from mouse (lane 8; diluted 1:1500); and the secondary antibodies alone (anti-human in lane 9; anti-mouse in lane 10).