The strips were incubated for 2 h with goat antihuman IgG conjugated with horseradish peroxidase (HRP, Zymed) at a dilution of 1:1000. Subsequently, strips were washed with PBST four times, 5 min each and a final wash with PBS after which immunoreactivity was visualized with the substrate o-d iaminobenzidine (DAB) (Zymed).