[In vitro study on the individual binding ability of omalizumab with free IgE]

Objective:To investigate the individual binding ability of omalizumab to free IgE and its effect on omalizumab action. Methods:A total of 28 serum samples were collected from patients with allergic rhinitis and divided into groups with high, medium and low concentrations of free IgE. Different doses of omalizumab were administered in vitro for inhibitory binding. Enzyme linked immunosorbent assay was used to detect changes in serum free IgE after inhibition. The inhibition constant of omalizumab on serum free IgE was calculated. At the same time, the binding ability of omalizumab and individual free IgE was analyzed. Results:In general, when 100% serum free IgE was inhibited, the omalizumab required was positively correlated with the original serum free IgE concentration（9.500±7.207, 8.636±7.375, and 0.786±0.857 for the high, medium, and low IgE concentration groups, respectively）. The dose of omalizumab required for inhibition of 50% free IgE in serum was significantly lower（0.049±0.071, 0.046±0.077, 0.048±0.048 in the high, medium, and low IgE concentrations groups, respectively）. The 100% and 50% inhibition constants of serum free IgE in different individuals were different to some extent. Conclusion:Overall, the amount of omalizumab required to achieve the same inhibitory effect is proportional to the IgE concentration. In some sensitive patients, partial binding inhibition of free IgE can occur even when omalizumab is administered at less than the recommended dose. The binding ability of serum free IgE and omalizumab was different in different individuals. If this factor is used as a reference for the individual dose of omalizumab in clinical medicine, it is possible to achieve the expected efficacy more accurately.