Active Interleukin 28B (IL28B)

Interleukin‑28B (IL28B), also designated IFN‑λ3, belongs to class‑II cytokine superfamily and exerts antiviral, antitumor and immunomodulatory bioactivities. It primarily binds IFNLR1 with high affinity and subsequently recruits IL10RB to assemble a functional heterodimeric receptor complex via protein‑protein interaction. This binding event triggers downstream JAK‑STAT signaling cascades, inducing interferon‑stimulated genes and mediating mucosal immune defense against invading pathogens.
Thus a functional ELISA assay was conducted to detect the interaction of recombinant IL28B and recombinant IFNLR1. Briefly, IL28B was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μL were then transferred to IFNLR1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-IL28B pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant IL28B and recombinant IFNLR1 was shown in Figure 1, the EC50 for this effect is 0.132µg/mL.