Affinity of antisera from rabbits No. 1 (●), No. 2 (○), No. 3 (▲), and No.4 (♦) for LND. LND-BSA was coated onto the microwell plates. Antiserum samples were mixed with LND and transferred into the microwells. Competitive binding reaction was allowed to proceed and the signals were generated as described by Darwish et al..