Impairment of cytomegalovirus-specific cellular immune response as a risk factor for cytomegalovirus disease in transplant recipients: [review]

Human cytomegalovirus (CMV) infection is common in most people but nearly asymptomatic in immunocompetent individuals. After primary infection the virus persists throughout life in a latent form in a variety of tissues, particularly in precursor cells of the monocytic lineage. CMV reinfection and occurrence of disease are associated with immunosuppressive conditions. Solid organ and bone marrow transplant patients are at high risk for CMV disease as they undergo immunosuppression. Antiviral treatment is effective in controlling viremia, but 10-15 percent of infected patients can experience CMV disease by the time the drug is withdrawn. In addition, long-term antiviral treatment leads to bone marrow ablation and renal toxicity. Furthermore, control of chronic CMV infection in transplant recipients appears to be dependent on the proper recovery of cellular immunity. Recent advances in the characterization of T-cell functions and identification of distinct functional signatures of T-cell viral responses have opened new perspectives for monitoring transplant individuals at risk of developing CMV disease.

Infecção pelo vírus Epstein-Barr em pacientes com lúpus eritematoso sistêmico / Epstein-Barr virus infection in patients with systemic lupus erythematosus

OBJETIVO: Verificar a associação entre a atividade do lúpus eritematoso sistêmico (LES) e a avidez das imunoglobulinas IgG anti-EBV. MÉTODOS: Analisou-se o sangue periférico de 66 pacientes distribuídos em dois grupos: 22 pacientes com LES em atividade e 44 pacientes com doença inativa. A presença e o índice de avidez de anticorpos IgG anti-EBV foram determinados pela técnica ELISA. (Enzygnost anti-EBV - Dade Behring). RESULTADOS: Identificou-se positividade no teste de detecção de IgG para EBV em 21 (95,5 por cento) pacientes do grupo LES ativo e em 40 (90,9 por cento) do grupo LES inativo. O índice de avidez alcançou valores 40 em 54 (88,5 por cento) pacientes, sendo 34 (85 por cento) do grupo LES inativo e 20 (95,2 por cento) do grupo LES ativo; em cinco (12,5 por cento) pacientes do grupo LES inativo, este índice ficou entre 20 e 40 e foi inferior a 20 em dois (3,3 por cento) pacientes. Adotando-se 20, 30 ou 40 como ponto de corte do índice de avidez, para diagnóstico de reativação da infecção por EBV, foram classificados como infecção reativada, nos grupos LES ativo e inativo, respectivamente: 1 (4,8 por cento) x 5 (12,5 por cento) pacientes, 1 (4,8 por cento) x 4 (10 por cento) pacientes e 1 (4,8 por cento) x 5 (12,5 por cento) pacientes. CONCLUSÃO: No presente estudo, não foi demonstrada associação entre a atividade do LES e a reativação do EBV. Esse fato parece indicar que a não eliminação dos linfócitos B infectados se deve à falha no mecanismo de apoptose ou à ação de linfócitos T citotóxicos, permitindo assim a progressão do LES.

OBJECTIVE: To verify the association of SLE activity to the avidity of IgG anti-EBV immune globulins. METHODS: Peripheral blood of 66 patients was analyzed, 22 had active SLE and 44 had inactive SLE. Presence and avidity index of IgG anti-EBV antibodies were determined by the ELISA method (Enzygnost® anti-EBV/IgG - Dade Behring). RESULTS: IgG anti-EBV test was positive for 21 (95.5 percent) patients in the active SLE group and 40 (90.9 percent) in the inactive group. The avidity index was 40 for 54 (88.5 percent) patients of which 34 (85 percent) belonged to the inactive SLE group and 20 (95.2 percent) to the active group. For 5 (12.5 percent) inactive SLE patients, the avidity index reached values ranging from 20 to 40; while for only 2 (3.3 percent) patients this index was lower than 20. Adopting 20, 30 or 40 as a cutoff point of the avidity index for diagnosis of reactivation of the EBV infection, the author classified as having reactivated infection, for active and inactive SLE groups, respectively: 1 (4.8 percent) x 1 (2.5 percent) patient; 1 (4.8 percent) x 4 (10 percent) patients and 1 (4.8 percent) x 5 (12.5 percent) patients. CONCLUSION: Association between EBV activity and SLE was not demonstrated. This appears to indicate that persistence of infected B lymphocytes may be due to failure in the apopotosis mechanism or to the action of T cytotoxic lymphocytes, permitting evolution of SLE.