SARS-CoV-2 Breakthrough Infections after Third Doses Boost IgG Specific Salivary and Blood Antibodies.

SARS-CoV-2 breakthrough infections, associated with waning immunity, increase systemic antibody levels. In this study, we analyzed the impact of the infection timing on the magnitude of the systemic humoral response and whether breakthrough infections also boost antibody levels in the salivary compartment. We observed that the combination of infection plus vaccination, regardless of infection timing, produced a sharp increase in systemic antibodies, which were higher in subjects infected after third doses. Moreover, despite high systemic antibody levels, breakthrough infections after dose three occurred and boosted antibody levels in the salivary compartment. These results suggest that current vaccination strategies against COVID-19 should be improved. Results also showed that determination of salivary antibodies against SARS-CoV-2 could be a valuable tool in disease prevalence studies, for the follow-up of vaccinated individuals, and to assist vaccination strategies against COVID-19, especially in settings where blood sampling cannot be fulfilled.

Humoral response to the BBIBP-CorV vaccine over time in healthcare workers with or without exposure to SARS-CoV-2.

SARS-CoV-2-specific humoral response was analyzed over time in a group of healthcare workers with or without exposure to SARS-CoV-2, who underwent vaccination with BBIBP-CorV (Sinopharm) vaccine in Argentina. Seroconversion rates in unexposed subjects after the first and second doses were 40 % and 100 %, respectively, showing a significant increase in antibody concentrations from dose 1 to dose 2 (p < 0.0001). The highest antibody concentrations were found in younger subjects and women, remaining significantly associated in a multivariable linear regression model (p = 0.005). A single dose of the BBIBP-CorV vaccine induced a strong antibody response in individuals with prior SARS-CoV-2infection, while a second dose did not increase this response. A sharp increase in antibody concentrations was observed following SARS-CoV-2 infection in those participants who became infected after the first and second doses (p = 0.008). Individuals with SARS-CoV-2 exposure prior to vaccination showed significantly higher anti-spike IgG antibody levels, at all-time points, than those not exposed (p < 0.001). Higher antibody titers were induced by a single dose in previously SARS-CoV-2 infected individuals than those induced in naïve subjects by two doses of the vaccine (p < 0.0001). Three months after the second dose both groups showed a decline in antibody levels, being more abrupt in unexposed subjects. Overall, our results showed a trend towards lower antibody concentrations over time following BBIBP-CorV vaccination. Sex and age seem to influence the magnitude of the humoral response in unexposed subjects while the combination of exposure to SARS-CoV-2 plus vaccination, whatever the sequence of the events was, produced a sharp increase in antibody levels. Evaluation of the humoral responses over time and the analysis of the induction and persistence of memory B and T cell responses, are needed to assess long-term immune protection induced by BBIBP-CorV vaccine.

Evaluacion de la produccion de citoquinas en enfermos de lepra / Evaluation of cytokine production in leprosy patients

El objetivo de este estudio fue evaluar la producción de citoquinas por células mononucleares periféricas (CMP) obtenidas de pacientes con lepra, cuando estas células son estimuladas con ConA, PPD o Myconacterium leprae. Medimos IL-2, IL-4, IFN- y e IL-6 en sobrenadantes libres de células, por enzimoinmunoensayos. Nuestros resultados no sugieren una clara associación entre una forma clínica de lepra y un perfil de secreción de citoquinas de tipo Th1 o Th2 en las CMP de los pacientes con lepra.

Efecto de linfocitos activados sobre la contractilidad cardiaca / The effect of activated lymphocytes on cardiac contractility

En esta serie de estudios se analizó la interacción del miocardio auricular aislado con linfocitos humanos normales estimulados con fitohemaglutinina o con los productos solubles liberados al sobrenadante. Los resultados indican que los linfocitos activados, de fenotipo CD4, inducen efectos inotrópicos positivos sobre la aurícula aislada de rata. Esta acción está vinculada a etapas de la estimulación linfocitaria que preceden la división blástica. El efecto estimulante de los linfocitos activados sería mediado por factores solubles liberados al sobrenadante. Entre ellos, la interleuquina-2 (IL-2) tendría fundamental importancia, ya que es posible disminuir la actividad biológica con anticuerpo monoclonal anti-IL-2 o por pre-incubación de las aurículas con anticuerpo monoclonal contra el receptor de IL-2 (anti-Tac): A concentraciones altas (10 unidades/ml), la IL-2 actúa por sí misma, pero en dosis menores requiere cofactores sinérgicos como el ácido araquidónico (AA) o el ionóforo de Ca A23187. Mediante estudios realizados con inhibidores, se demuestra que la IL-2 dispara la activación del ciclo de los fosfoinosítidos en el corazón a través de la fosfolipasa C. Luego, la proteína que los infiltrados linfocitarios presentes en cardiomiopatías inflamatorias podrían provocar cambios similares en la contractilidad. Por otra parte, hay que tener en cuenta que estos trastornos pueden ocurrir en el tratamiento masivo con IL-2