Fig 8. Approaches to block multivalent interfering substances or HAMAs may improve the ELISA selectivity for MPO-DNA complexes in human plasma.

A) and C) Serially diluted calibrator or B) and D) plasma samples diluted at 1:10, 1:30 and 1:100 (with sample diluent of the ABTS ELISA Buffer Kit) were supplemented A) and B) without (w/o) or with increasing doses (10 μg/ml, 100 μg/ml, 500 μg/ml) of protein A-purified mouse IgG from normal mouse serum or C) and D) without (w/o) or with graded doses (0.1%, 1%, 10%) of TRU Block Ready reagent. The further procedure of the MPO-DNA complex ELISA was performed according the initial protocol in microwells coated with MPO antibody, isotype control or left uncoated. Note that data points of uncoated microwells overlap in 8A and C. E) Plasma was diluted 1:100 without (w/o) or with supplementation of 10% TRU Block Ready reagent. The further procedure of the MPO-DNA complex ELISA was performed according to the initial protocol in microwells coated with MPO antibody or isotype control. F) and G) Plasma of two donors at dilutions of 1:100, 1:200 and 1:400 was supplemented with 10% TRU Block Ready reagent. The further procedure of the MPO-DNA complex ELISA was based on the initial protocol with microwells coated with MPO antibody or isotype control or left uncoated.