[Respiratory allergy in children and passive smoking]. / Allergie respiratoire de l'enfant et tabagisme passif.

Environmental tobacco smoke interacts with the respiratory mucosa by irritation and/or inflammation. Environmental tobacco smoke seems also modulate humoral and cellular immune activity. Thus, environmental tobacco smoke, in all children, increases the risk of superior and inferior airway infections, modifies the growth and the natural evolution of the respiratory function, increases the occurrence of asthma and exacerbates the symptoms of asthma, and creates or exacerbates a bronchial hyperresponsiveness. In atopic children (defined by the presence of at least one positive allergy skin test), environmental tobacco smoke increases the risk of respiratory allergy and exacerbates the symptoms of respiratory allergy. Parental environmental tobacco smoke is a universal toxic which must be avoided in both allergic and non-allergic children.

[Acute asthmatic crisis in children]. / La crise d'asthme aigu grave de l'enfant.

Acute asthma attack in children is an attack responsible for life-threatening acute respiratory distress with partial or no response to bronchodilator drugs. The severity of the episode needs to be quickly evaluated. This presupposes a perfect knowledge of the clinical signs of severity. Treatment is urgent and first based on the administration of high doses of inhaled short-acting beta 2-agonists. In the more obstructed children, anti-cholinergic drugs can be added to nebulized beta 2-agonists. Because of their delayed effect, systemic steroids require an early prescription. Symptomatic treatments are: urgent hospitalization, oxygen if needed, proper hydratation. Continuous nebulization or intravenous perfusion of beta 2-agonists are prescribed with cardiac monitoring when no objective improvement is noted. Admission into the pediatric intensive care unit when bronchial obstruction continues will permit the association of bronchodilator drugs and the proposal of mechanical ventilation if needed. When the episode is resolved, a prophylactic treatment using inhaled corticosteroids must be prescribed. Clinical and spirometric follow-up has to be organized, and the patient and his/her family have to be educated.

[Ontogeny of the immune system]. / Ontogénie du système immunitaire.

The newborn immune system differs quantitatively and functionally from adults. At birth, the immune system is partially immature, resulting in deficiency in cell-mediated cytolysis, immunoglobulin synthesis and cytokine production. The most clearly defined deficit in neonatal phagocytosis defenses is diminished neutrophil storage. T cell function is diminished, including T cell-mediated cytotoxicity and T cell help for B cell differentiation. Selective decreases in cytokine production by T cells may contribute to all of these deficits. One of the fundamental differences between adults and newborns for T cell functions resides in whether or not the patient had prior exposure to antigens. Significant immune responses to antigens can be obtained in the neonatal period. These responses are qualitatively different from those induced in adults with a predominance of TH2 pattern.