| - Respiratory Syncytial Virus (RSV) is associated with most of the acute viral respiratory tract infections causing hospitalization with a peak during the first months of life. Many clinical trials of RSV vaccine candidates are being carried out. The aim of this study was to obtain epidemiologic information to give suggestions on target populations and prevention strategies before the introduction of new vaccines or monoclonal antibodies. We retrospectively evaluated, over a 5-year period (September 2014-August 2019), a population of hospitalized Italian children aged 0-6 years with a laboratory confirmed diagnosis of RSV infection. Risk factors, seasonality of RSV infection, distribution according to age, cases of coinfections and reinfections and cases needing Intensive Care Unit were evaluated. Hospitalizations due to RSV were 624 in the period under study. The peak was found between November and April, with 80.4% of cases recorded between December and February. 62.5% of cases were found in children under three months of age and 41% in children under 30 days old. The need for intensive care was associated with younger ages, with 70.9% of cases in children below three months of age. Unless the incoming vaccines demonstrate a strong herd protection effect, preventive strategies should be aimed at newborns or at maternal immunization.
| - Acute lymphoblastic leukemia (ALL) is the most common cancer in children around the globe. Mexico City has one of the highest incidence rates of childhood leukemia worldwide with 49.5 cases per million children under the age of 15 which is similar to that reported for Hispanic populations living in the United States. In addition, it has been noted a dismal prognosis in Mexican and Hispanic ALL pediatric population. Although ALL, like cancer in general, has its origins in endogenous, exogenous, and genetic factors, several studies have shown that the immune system also plays a deterministic role in cancer development. Among various elements of the immune system, T lymphocytes and NK cells seem to dominate the immune response against leukemia. The aim of the present study was to perform a phenotypic and functional characterization of NK cells in ALL Mexican children at the moment of diagnosis and before treatment initiation. A case-control study was conducted by the Mexican Interinstitutional Group for the Identification of the Causes of Childhood Leukemia (MIGICCL). 41 cases were incident ALL children younger than 17 years old and residents of Mexico City. 14 controls were children without leukemia, matched by age and sex with cases. NK cell function was evaluated by degranulation assays towards K562 cells and SLAM-associated protein (SAP) expression was measured by intracellular staining. All assays were performed using peripheral blood mononuclear cells from controls and patients. The results indicate that NK mediated cytotoxicity, measured by CD107a degranulation assays in response to K562 cells, was reduced in ALL patients compared to controls. Interestingly, an impaired NK cell killing of target cells was not equally distributed among ALL patients. In contrast to patients classified as high-risk, standard-risk patients did not display a significant reduction in NK cell-mediated cytotoxicity. Moreover, patients presenting a leukocyte count ≥ 50,000xmm3 displayed a reduction in NK-cell mediated cytotoxicity and a reduction in SAP expression, indicating a positive correlation between a reduced SAP expression and an impaired NK cell-mediated citotoxicity. In the present study it was observed that unlike patients with standard-risk, NK cells from children presenting high-risk ALL, harbor an impaired cytotoxicity towards K562 at diagnosis. In addition, NK cell function was observed to be compromised in patients with a leukocyte count ≥50,000xmm3, where also it was noticed a decreased expression of SAP compared to patients with a leukocyte count <50,000xmm3. These data indicate NK cell-mediated cytotoxicity is not equally affected in ALL patients, nevertheless a positive correlation between low SAP expression and decreased NK cell-mediated cytotoxicity was observed in ALL patients with a leukocyte count ≥50,000xmm3. Finally, an abnormal NK cell-mediated cytotoxicity may represent a prognostic factor for high-risk acute lymphoblastic leukemia.