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ABSTRACT: Assessment of specific antibody (Ab) production to polysaccharide antigens is clinically relevant, identifying patients at risk for infection by encapsulated bacteria and thus enabling a more rigorous selection of patients that can benefit of immunoglobulin replacement therapy. Classically, the gold-standard test is the measurement of antibody production to pure polysaccharide pneumococcal (PPV) immunization. Several factors, including introduction of conjugate vaccination schedule, serotyping analysis, high baseline Ab levels, have hindered the evaluation of polysaccharide antigens. This is even more difficult in secondary immunodeficiencies (SID), where patients can show secondary responses despite lack of primary antibody responses and present with recurrent or severe infections. Assessment of specific Ab production to pure Salmonella typhi Vi polysaccharide (TV) immunization has been proposed as a complementary test to PPV, given its low seroprevalence. To set the optimal cut-off value for PPV and TV response in SID, we tested different biostatistical methodologies, including ROC analysis, Youden index, Union index and Closest-topleft in a cohort of 42 SID patients and 24 healthy controls. The statistically chosen cut-offs value pre-post TV Ab ratio was ≥5, (sensitivity of 90%, specificity of 100%) and a postvaccination TV concentration of 28.5 U/mL (sensitivity of 90%, specificity of 95%), showing relevant clinical correlate.

Resumen: Antecedentes: La neuromielitis óptica (NMO) es una enfermedad predominantemente humoral mediada por anticuerpos IgG-NMO/AQP-4. Sin embargo, no se conoce bien la contribución de las diferentes subpoblaciones de células B y T en su patogenia o en la respuesta a los tratamientos. Objetivos: Describir los cambios clínicos e inmunológicos asociados al tratamiento con inmunoglobulinas intravenosas (Ig-IV) y rituximab (RTX) en una paciente con un brote grave de NMO y síntesis intratecal de IgG-NMO/AQP-4 que no había respondido a metilprednisolona y recambio plasmático. Métodos: Se analizaron, de forma secuencial en el LCR y en la sangre periférica (SP), las subpoblaciones linfocitarias mediante citometría de flujo multiparamétrica y los IgG-NMO/AQP-4, antes y después del tratamiento con Ig-IV y RTX. Resultados: En el LCR antes del tratamiento, y comparado con la SP, predominaban las células T CD4+ y estaban menos representadas las T CD8+ y las B CD19+. Tras el tratamiento, el porcentaje de células T CD4+ se mantuvo alto, el de T CD8+ aumentó y el de B CD19+ disminuyó, aunque menos que en la SP. Al comparar los LCR se vio que tras la terapia el porcentaje de células T CD8+ memoria efectoras y efectoras había aumentado, y el de células B memoria IgM y el de células B con cambio de isotipos, disminuido. Los cambios observados fueron paralelos a la negativización de los IgG-NMO/AQP-4 y a la mejoría clínica. Conclusiones: Nuestros hallazgos confirman que, además de una respuesta inmunitaria humoral intratecal durante el brote de NMO, subpoblaciones específicas de células B y T participan en la modulación de la inflamación dentro y fuera del sistema nervioso central. Abstract: Background: There is increasing evidence supporting that neuromyelitis optica (NMO) is an inflammatory humoral mediated disorder associated with NMO-IgG/AQP-4 antibodies. However, little is known about the subsets of B cells and T cells that contribute to the pathogenesis or therapy response. Objectives: To describe the clinical and immunological changes associated with intravenous immunoglobulins (IV-Igs) plus rituximab (RTX) in a patient with a severe acute attack of NMO and intrathecal synthesis of NMO-IgG/AQP-4, who previously did not respond to intravenous methylprednisolone and plasma exchange. Methods: We sequentially analysed the levels of NMO-IgG/AQP-4 by immunohistochemistry, and B and T cells subsets by multiparametric flow-cytometry, in the CSF and peripheral blood (PB), before and alter IV-Igs plus RTX therapy. Results: In the CSF before treatment, and compared with PB, there was a higher percentage of CD4+ T cells and a lower percentage of CD8+ T cells and CD19+ B cells. After therapy, the percentage of CD4+ T cells remained high, and that of CD8+ T cells increased. The observed decrease in the percentage of CD19+ B cells was lower than in the PB. When the CSF was compared, it was found that the percentage of effector-memory and effector CD8+ T cells had increased after therapy, and that of IgM memory B cells and switched-memory B cells decreased. The observed changes paralleled the decrease of NMO-IgG/AQP-4 results to negative and the clinical improvement. Conclusions: Our findings confirm that, besides intrathecal humoral immune response against AQP4, B and T cell subsets are involved in the modulation of inflammation within and outside the central nervous system. Palabras clave: Neuromielitis óptica, Líquido cefalorraquídeo, Autoanticuerpos Anti-acuaporina-4, Subclases de células B CD19+ y T CD8+, Keywords: Neuromyelitis optica, Cerebrospinal fluid, Anti-aquaporin-4 autoantibodies, CD19+ and CD8+ T cell subsets

Background: There is increasing evidence supporting that neuromyelitis optica (NMO) is an inflammatory humoral mediated disorder associated with NMO-IgG/AQP-4 antibodies. However, little is known about the subsets of B cells and T cells that contribute to the pathogenesis or therapy response. Objectives: To describe the clinical and immunological changes associated with intravenous immunoglobulins (IV-Igs) plus rituximab (RTX) in a patient with a severe acute attack of NMO and intrathecal synthesis of NMO-IgG/AQP-4, who previously did not respond to intravenous methylprednisolone and plasma exchange. Methods: We sequentially analysed the levels of NMO-IgG/AQP-4 by immunohistochemistry, and B and T cells subsets by multiparametric flow-cytometry, in the CSF and peripheral blood (PB), before and after IV-Igs plus RTX therapy. Results: In the CSF before treatment, and compared to PB, there was a higher percentage of CD4+ T cells and a lower percentage of CD8+ T cells and CD19+ B cells. After therapy, the percentage of CD4+ T cells remained high, and that of CD8+ T cells increased. The observed decrease in the percentage of CD19+ B cells was lower than in the PB. When the CSF was compared, it was found that the percentage of effector-memory and effector CD8+ T cells had increased after therapy, and that of IgM memory B cells and switched-memory B cells decreased. The observed changes paralleled the decrease of NMO-IgG/AQP-4 results to negative and the clinical improvement. Conclusions: Our findings confirm that, besides intrathecal humoral immune response against AQP4, B and T cell subsets are involved in the modulation of inflammation within and outside the central nervous system. Resumen: Antecedentes: La neuromielitis óptica (NMO) es una enfermedad predominantemente humoral mediada por anticuerpos IgG-NMO/AQP-4. Sin embargo, no se conoce bien la contribución de las diferentes subpoblaciones de células B y T en su patogenia o en la respuesta a los tratamientos. Objetivos: Describir los cambios clínicos e inmunológicos asociados al tratamiento con inmunoglobulinas intravenosas (Ig-IV) y rituximab (RTX) en una paciente con un brote grave de NMO y síntesis intratecal de IgG-NMO/AQP-4 que no había respondido a metilprednisolona y recambio plasmático. Métodos: Se analizaron, de forma secuencial en el LCR y en la sangre periférica (SP), las subpoblaciones linfocitarias mediante citometría de flujo multiparamétrica y los IgG-NMO/AQP-4, antes y después del tratamiento con Ig-IV y RTX. Resultados: En el LCR antes del tratamiento, y comparado con la SP, predominaban las células T CD4+ y estaban menos representadas las T CD8+ y las B CD19+. Tras el tratamiento, el porcentaje de células T CD4+ se mantuvo alto, el de T CD8+ aumentó y el de B CD19+ disminuyó, aunque menos que en la SP. Al comparar los LCR se vio que tras la terapia el porcentaje de células T CD8+ memoria efectoras y efectoras había aumentado, y el de células B memoria IgM y el de células B con cambio de isotipos, disminuido. Los cambios observados fueron paralelos a la negativización de los IgG-NMO/AQP-4 y a la mejoría clínica. Conclusiones: Nuestros hallazgos confirman que, además de una respuesta inmunitaria humoral intratecal durante el brote de NMO, subpoblaciones específicas de células B y T participan en la modulación de la inflamación dentro y fuera del sistema nervioso central. Keywords: Neuromyelitis optica, Cerebrospinal fluid, Anti-aquaporin-4 autoantibodies, CD19+ and CD8+ T cell subsets, Palabras clave: Neuromielitis óptica, Líquido cefalorraquídeo, Autoanticuerpos Anti-acuaporina-4, Subclases de células B CD19+ y T CD8+