RESUMO
To analyze the in vivo biological effect of anti-interferon beta (IFN-beta) neutralizing antibodies (NABs), blood concentrations of neopterin, beta2microglobulin (Beta2-MG), mRNA-dependent myxovirusresistant protein A (MxA) and dsRNA-dependent protein kinase (PKR) were measured before (predose) and 24 hours after (postdose) IFN-beta administration in 49 patients with multiple sclerosis (MS) with (n = 25) and without (n = 24) NABs. The results indicated that predose levels of MxA-mRNA and PKR-mRNA were highly variable [coefficient of variation (CV) > 100%] among patients. A lower inter-individual variability was observed for pre-dose levels of Beta2-MG and neopterin (CVs of 29% and 44%, respectively). Significantly lower pre- and post-dose blood levels of IFN induced markers, except for postdose PKR-mRNA (p = 0.09), were seen in NAB+ compared with NAB-patients and between patients with high (> 200 t(1/10)) and low ( pound 200 t(1/10)) NAB titers. A significant inverse correlation between NAB titer and pre-dose levels of the above IFN-induced markers was found. In summary, our findings confirm that NABs affect absolute concentrations of IFN-beta induced markers and suggest that such an effect occurs in a titer-dependent manner.
Assuntos
Anticorpos/sangue , Interferon beta/uso terapêutico , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/imunologia , Adulto , Reações Antígeno-Anticorpo , Avaliação da Deficiência , Feminino , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica/efeitos dos fármacos , Humanos , Interferon beta/sangue , Interferon beta/imunologia , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/sangue , Proteínas de Resistência a Myxovirus , Neopterina/sangue , Testes de Neutralização/métodos , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estatísticas não Paramétricas , Microglobulina beta-2/genética , Microglobulina beta-2/metabolismo , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismoRESUMO
Neutralizing antibodies (NAbs) may compromise interferon (IFN) clinical efficacy in patients with multiple sclerosis (MS) receiving IFN-beta treatment. When bioassays are used for anti-IFN-beta antibody detection, they are unable to discriminate between NAbs or other interfering substances with anti-IFN activity. Here we report the development of an anti-IFN-beta Western blot method that facilitates the detection of IFN low-titred antibodies and characterizes such low neutralizing activity as specifically due to the presence of particular IFN antibodies. The assay was characterized using serum samples from patients with MS treated with IFN-beta. It was developed by adding anti-IFN-positive antibody sera to Dynabeads M-280 tosylactivated followed by Western blot analysis. All sera samples from MS patients with IFN-betala NAbs (< or = 50 t1/10) proved to be antibody-positive using this new method and, more importantly, four of 27 binding antibody-negative sera samples were scored as IFN antibody-positive. The method was found to be rapid, specific and sensitive and consistent with respect to well-established antiviral neutralization or commercial enzyme-linked immunosorbent assays.
