Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Immunoadsorption
Immunoadsorption (IA) selectively removes certain plasma proteins. IA can be specific (only removing antibody specific for single antigen) or nonspecific (removing all antibodies). Although several IA systems are available worldwide, none are currently used in the United States.
This chapter discusses only IA using staphylococcal protein A (SPA) columns, which remove immunoglobulin, as an example of a selective system. SPA is a cell wall component of certain strains of Staphylococcal aureus and has high affinity for Fc portion of IgG and for aggregated IgG and IgG-containing immune complexes. SPA binds strongly to IgG1, IgG2, and IgG4 and variably with IgG3, IgM, and IgA. Additionally, IA has immunomodulatory affects, including activating complement by the alternate pathway and reducing circulating immune complexes by altering antigen–antibody ratios.
Protein A Immunoadsorption
Two extracorporeal SPA devices, Prosorba and Immunosorba, use highly purified SPA linked to a solid matrix to selectively remove immunoglobulins from plasma. The Prosorba column (Fresenius Kabi, Redmond, WA) contained SPA immobilized on a silica matrix, which removes free immunoglobulins and immune complexes. As of 2006, Prosorba column is no longer commercially available. Immunosorba column (Fresenius Kabi AG, Bad Homburg, Germany), consists of SPA linked to a sepharose matrix. The process involves separation of plasma in a cell separator, passing 7–9 L of plasma alternatively through one of two parallel columns, and returning processed plasma to the patient. Treatment of 2.5 plasma volumes reduces plasma immunoglobulin concentrations: IgG1 (97%), IgG2 (98%), IgG3 (40%), IgG4 (77%), IgM (56%), and IgA (55%).
Adverse Effects
Most procedures result in minor, but not major, complications. Common adverse effects include chills, low-grade fever, musculoskeletal pain, hypotension, nausea, and vomiting. Short-term flare in joint pain and swelling may appear within 1 hour of the procedure and last up to 2 hours. Severe respiratory and cardiovascular toxicities can occur, rarely resulting in fatality. Additionally, the use of IA is contraindicated in patients taking angiotensin converting enzyme inhibitor (ACEI).
Indications
IA, or therapeutic plasma exchange (TPE), can be used to treat various immune-mediated disorders. However, unlike IA, TPE removes pathogenic and nonpathogenic (i.e., coagulation factors) substances from plasma nonselectively.
Atopic Dermatitis, Recalcitrant
Atopic dermatitis (AD) is the most common chronic relapsing skin disease, frequently affecting children. AD-affected individuals have elevated levels of IgE and are predisposed to allergic rhinitis and asthma later in life. IA has been used to reduce serum IgE; however, short-term decreases are followed by rebound elevation within weeks after discontinuation of IA.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here