RESUMO
Atomic force microscopy (AFM) is being increasingly used to directly measure protein interactions in nearly physiological environments. Here, protocols for atomic force microscopy (AFM) for visualization of antigen-antibody complexes are presented. The technique is used to demonstrate complexes formed by rheumatoid arthritis patient antibodies with lipopolysaccharide (LPS) isolated from P. mirabilis (O3) strain S1959 and a synthetic antigen (LPS epitope of 6 N-alpha-(D-galacturonoyl)-L-lysine residues).
Assuntos
Complexo Antígeno-Anticorpo/isolamento & purificação , Artrite Reumatoide/imunologia , Proteus mirabilis/metabolismo , Anticorpos Antibacterianos/metabolismo , Epitopos/imunologia , Humanos , Lipopolissacarídeos/imunologia , Microscopia de Força AtômicaRESUMO
Expenditure on screening blood donations in developing countries can be reduced by testing donations in pools. This study evaluated serological screening in pools for hepatitis B virus (HBV) at the Israeli national blood bank and a hospital blood bank in Gaza, the Palestinian Authority. The accuracy of HBV surface antigen (HBsAg) enzyme immunoassay performed on pools of 3-24 samples was compared with individual tests. Delay in detecting positive samples due to dilution in pools and the possibility of antibody-antigen neutralization were analyzed. The sensitivity of pooled testing for HBsAg was 93-99%, prolonging the window period by 5 days (8.3%). Neutralization of HBsAg by hepatitis B surface antibodies (anti-HBs) could be minimized by testing immediately after pooling. Serological testing for HBsAg in pools may be performed using manually created pools of up to six samples, with 5% loss in sensitivity and a risk of neutralization by anti-HBs present in the donor population. Pooling can therefore be considered as an option only in countries with a low prevalence of HBV.
Assuntos
Complexo Antígeno-Anticorpo/isolamento & purificação , Doadores de Sangue , Anticorpos Anti-Hepatite B/isolamento & purificação , Antígenos do Núcleo do Vírus da Hepatite B/isolamento & purificação , Antígenos de Superfície da Hepatite B/isolamento & purificação , Hepatite B Crônica/prevenção & controle , Complexo Antígeno-Anticorpo/sangue , Bancos de Sangue , Análise Custo-Benefício , Seleção do Doador , Estudos de Viabilidade , Anticorpos Anti-Hepatite B/sangue , Antígenos do Núcleo do Vírus da Hepatite B/sangue , Antígenos de Superfície da Hepatite B/sangue , Hepatite B Crônica/transmissão , Humanos , Imunoensaio/métodos , Sensibilidade e Especificidade , Carga ViralRESUMO
Extracorporeal immunoadsorption of plasma to remove IgG and circulating immune complexes (CIC) was evaluated as a therapy for adults with treatment-resistant immune thrombocytopenic purpura (ITP). Seventy-two patients with initial platelet counts less than 50,000/microL who had failed at least two other therapies were studied. They received an average of six treatments of 0.25 to 2.0 L plasma per procedure over a 2- to 3-week period using columns of staphylococcal protein A-silica (PROSORBA immunoadsorption treatment columns; IMRE Corp, Seattle, WA). The treatments caused an acute increase in the platelet count to greater than 100,000/microL in 18 patients and to 50,000 to 100,000/microL in 15 patients. The median time to response was 2 weeks. Responses were transient (less than 1 month duration) in seven of those patients (10%), but no additional relapses were reported over a follow-up period of up to 26 months (mean of 8 months). Clinical responses were associated with significant decreases in specific serum platelet autoantibodies (including anti-glycoprotein IIb/IIIa), platelet-associated Ig, and CIC. Thirty percent of treatments were associated with transient mild to moderate side effects usually presenting as a hypersensitivity-type reaction. Continued administration of failed therapies for ITP, which always included low-dose corticosteroids (less than or equal to 30 mg/d), had no demonstrable influence on the effectiveness of immunoadsorption treatment but did depress the incidence and severity of side effects. The degree of effectiveness of protein A immunoadsorption therapy in patients with treatment-resistant ITP is promising and further controlled studies in this patient population are warranted.