IgG1+ B-cell immunity predates IgE responses in epicutaneous sensitization to foods.

BACKGROUND: The generation of IgE-mediated food allergy in humans is silent and only diagnosed upon manifestation of clinical symptoms. While experimental models have been used to investigate some mechanisms of allergic sensitization, the generation of humoral immunity and memory remains to be elucidated. Here, we defined the evolution of allergen-specific B-cell responses during epicutaneous sensitization to foods. METHODS: Wild-type and genetic knockout animals, and drug or antibody strategies for cell depletion and immunoglobulin signaling blockade were used to investigate epicutaneous sensitization and disease progression; we analyzed allergen-specific germinal centers and IgG1+ memory B cells by flow cytometry, evaluated humoral responses, and determined clinical reactivity (anaphylaxis). RESULTS: Epicutaneous sensitization caused microscopic skin damage, inflammation, and recruitment of activated dendritic cells to the draining lymph nodes. This process generated allergen-specific IgG1+ germinal center B cells, serum IgG1, and anaphylaxis that was mediated by the alternative pathway. Whether we used peanut and/or ovalbumin from the egg white for sensitization, the allergen-specific IgG1+ memory compartment predominantly exhibited an immature, pro-germinal center phenotype (PDL-2- CD80- CD35+ CD73+ ). Subsequent subclinical exposures to the allergen induced IgE+ germinal center B cells, serum IgE, and likely activated the classical pathway of anaphylaxis. CONCLUSIONS: Our data demonstrate that IgG1+ B-cell immunity against food allergens in epicutaneous sensitization precedes the generation of IgE responses. Therefore, the assessment of allergen-specific cellular and humoral IgG1+ immunity may help to identify individuals at risk of developing IgE-mediated food allergy and hence provide a window for therapeutic interventions.

Myocardial assessment using tissue doppler imaging in preterm very low-birth weight infants before and after red blood cell transfusion.

OBJECTIVE: To investigate myocardial velocities in anemic very low-birth weight (VLBW) preterm infants, pre and post red blood cells transfusion using tissue Doppler imaging echocardiography. STUDY DESIGN: Forty-eight VLBW preterm infants34 weeks and>2 weeks old were prospectively divided: Transfused symptomatic infants (Hematocrit (Hct)<0.30 (n=32)) and non transfused asymptomatic controls (control 1, Hct >0.30 (n=9) and control 2, Hct <0.30 (n=7)). Echocardiography was performed before and 3-5 days after transfusion in the transfused, and the controls were studied at similar intervals. Non parametric tests were used for statistical analysis. RESULT: Left ventricular (LV) systolic velocity increased (transfused (4.6±0.70 vs 6.0±0.65, P<0.01)) as did LV diastolic velocities (P<0.01) without significant difference over time in each control. The percentage change in LV velocity following transfusion correlated negatively (ρ=0.36) with pre transfusion Hct. CONCLUSION: There is a significant increase in myocardial performance following transfusion, which is related to the severity of the anemia.

Poor compliance with child safety restraint use while travelling.

Road traffic accidents are a leading cause of death of children. It is the law that all children should be appropriately secured when traveling in vehicles. The aim of this study was to evaluate parental conformity with these regulations and to test if advice given at a Paediatric outpatient clinic could improve compliance. Two groups were assigned, an intervention group (parents given an information leaflet and a clear explanation about appropriate restraints for their children) and a non-intervention group (received no information). They were contacted again after 2 months and asked regarding compliance. A total of 394 children from 186 families were initially given the questionnaire. Nearly one third of children (29.2%) were not using any restraint while travelling rising to 35.3% on follow up. This study concluded that once off parental education made negligible difference to an already inconsistent and haphazard approach to compliance with safety regulations.