Ex Vivo Removal of IgE in Atopic Asthma by Extracorporeal Plasmoimmunoadsorption (EPIA): Development of a Clinical Adsorbent

Abstract

We have developed an immunoadsorbent (IA) for ex vivo removal of IgE after in vitro screening of matrix (Sepharose and tresyl-activated Toyopearl) and ligand (monospecific rabbit polyclonal anti-IgE antiserum and monoclonal antibodies (Abs) or their Fab fragments). Specific adsorptive capacity (SAC) for IgE was maximal in Sepharose-based IA with both types of Abs. Fab-containing IA on Sepharose retained 70-90% of the SAC of native Ab-containing IA. Toyopearl-based IA showed comparable SAC under static conditions but worked unsatisfactorily under continuous flow conditions. To assess the complement-activating capacity (CAC) of IA in vitro anaphylatoxin (C3a, C4a, C5a) generation was applied. CAC was directly related with the amount of immobilized Ab ligand, without depending on Ab specific activity. Fab-containing IA showed more CAC than native Ab-containing IA, and polyclonal IA more than monoclonal IA. Therefore, IA for IgE apheresis were prepared from native monoclonal Abs and CNBr-activated Sepharose CL 4B under aseptic conditions and packed into a glass column. This IA was used in 17 clinical IgE apheresis treatments of five atopic asthma patients. No substantial side effects were observed; in vivo IA effectively removed IgE from plasma (83 to 98%).

In Vitro Evaluation of Biospecific and Pseudobiospecific Ligands Aimed at Extracorporeal Treatment for Immunoglobulin E Removal

“…Anti‐IgE (the ligand used for removal of IgE from the extracorporeal circulation) binds IgE molecules with high affinity through interaction with Fab portion (antibody–antigen binding), whereas Lc probably binds through interaction with d ‐manose and d ‐glucose (21), with less specificity. The selectivity of anti‐IgE for total IgE was confirmed in vivo by specific adsorptive capacity for IgE from 83 to 98%, after 1200–3400 mL of processed pv (6). Some clinical IgE apheresis sessions were carried out for patients suffering from atopic asthma, containing high initial concentrations of IgE (6).…”

“…The selectivity of anti‐IgE for total IgE was confirmed in vivo by specific adsorptive capacity for IgE from 83 to 98%, after 1200–3400 mL of processed pv (6). Some clinical IgE apheresis sessions were carried out for patients suffering from atopic asthma, containing high initial concentrations of IgE (6). Although it produces good results and has efficiency, the Sepharose‐CL‐4B‐anti‐IgE is very expensive.…”

“…Regarding the in vitro simulation of therapeutic immunoadsorption, the R% of IgE for Lc‐agarose was lower than that for Sepharose‐CL‐4B‐anti‐IgE (6). The differences in adsorption behavior between Lc‐agarose and Sepharose‐CL‐4B‐anti‐IgE are due to the type of interaction between the ligand and adsorbed molecule.…”

“…In this approach, the patient’s plasma is loaded to a column containing an agarose immobilized ligand in order to remove IgE returning the nonadsorbed proteins to the patient. Lebedin et al (6) used monoclonal antibodies anti‐IgE immobilized on Sepharose CL 4B in 17 clinical IgE apheresis treatments of five atopic asthma patients, and they effectively removed IgE from plasma (83% to 98%). In spite of good results, the ligands employed in this system are anti‐IgE antibodies, which are expensive and difficult to purify (7,8).…”

A high‐affinity monoclonal anti‐IgE antibody for depletion of IgE and IgE‐bearing cells

“…Actually, clinical studies performed with column‐bound anti‐IgE performed by Lebedin et al. (34) demonstrated that such a treatment is well tolerated and may reduce IgE levels.…”