Ex vivo removal of IgE in atopic asthma by extracorporeal plasmoimmunoadsorption (EPIA): development of a clinical adsorbent.

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%).

Serum levels of interleukin 4, interleukin 6 and interferon-gamma following in vivo isotype-specific activation of IgE synthesis in humans.

It is now generally accepted that interleukin 4 (IL4), interleukin 6 (IL6) and interferon-gamma (IFN gamma) play main roles in the regulation of human IgE synthesis. This concept is based mainly on in vitro data. To obtain corresponding in vivo data, we determined IL4, IL6 and IFN gamma by immunoassays in sera collected from 4 atopic patients following a clinical trial of selective IgE apheresis (plasmaimmunoadsorption). This treatment removes several milligrams of IgE from patient's blood and is suggested to induce strong and isotype-specific activation of the IgE system. Serum IgE levels restored rapidly within 3-5 days after IgE apheresis. However, very low and constant levels of IL4 (from less than 50 to 130 pg/ml) and IL6 (from less than 300 to 920 pg/ml) were detected in the sera of the treated patients. Serum IFN gamma was absent before treatment (concentrations less than 0.5 U/ml) and increased to low but detectable levels (0.90 and 8.05 U/ml) on the day following the last IgE apheresis in 2 of 4 patients. In our opinion, the data presented argue against in vivo participation of IL4 and IL6 in the activation of the human IgE system, at least in atopic patients under constant allergen exposure.

[Immunosorption in the treatment of bronchial asthma patients. The late results of a 5-year observation]. / Immunosorbtsiia v lechenii bol'nykh bronkhial'noi astmoi. Otdalennye rezul'taty 5-letnego nabliudeniia.

Analysis was made of the long-term results of immunosorption in 30 patients afflicted with bronchial asthma. 26 patients (14 with hypersensitivity to home dust allergen and 12 with pollenosis associated with hypersensitivity to timothy pollen allergen) received extracorporeal immunosorption: 1 patient underwent extracorporeal lymphocytic perfusion, 3 patients extracorporeal anti-IgE-plasma immunosorption. The use of immunosorption provides short-term beneficial results. The follow-up for 1 to 5 years revealed that the procedure exerted a beneficial action in 24 patients. In 6 patients, immunosorption did not produce any noticeable effect or else it was short-lived. External respiratory function differed substantially before and after immunosorption and correlated with the clinical improvement of the patients' status. Examination of cellular humoral immunity permitted the positive dynamics to be established in the content of T-lymphocyte subpopulations, the total and specific IgE.

[The clinical use of immunosorption: problems and perspectives]. / Klinicheskoe primenenie immunosorbtsii: problemy i perspektivy.

The data concerning clinical use of extracorporeal immunoadsorption are summarized. At present, broad use of this therapeutic approach is hampered by several technological and medical problems such as incomplete biocompatibility of carrier, pyrogenic reactions, ligand "leakage" and rebound phenomena. However, the technology of ex vivo removal is much more developed, than the fundamental knowledge of relevant target substance to be removed in specific clinical situation. The appropriate denomination of such "targets" should provide this method with a wide application field in clinical medicine.