CD40 ligand expression deficiency in a female carrier of the X-linked hyper-IgM syndrome as a result of X chromosome lyonization.

We report on the case of a girl with an immune deficiency characterized by recurrent infections of the upper and lower respiratory tract, low IgG and IgA serum levels as well as deficiency of the in vivo antibody response. Since this patient is the sister of a boy affected with a hyper-IgM syndrome due to a defect in CD40 ligand (CD40L) expression, the involvement of CD40L in this phenotypic expression was investigated. A very low fraction of activated T cells (5%) in this female patient expressed CD40L. This resulted from the presence of a heterozygous CD40L nonsense mutation associated with a skewed pattern of X chromosome inactivation as determined by methylation pattern analysis. Although carriers of X-linked hyper-IgM are considered to be asymptomatic, this study indicates that extreme lyonization of the normal X can lead to a mild expression of the hyper-IgM syndrome which is similar to common variable immune deficiency (CVID). Therefore, it is possible that some cases of CVID in females represent partial deficiency of CD40L expression in carriers of the CD40L mutation.

[Value and limits of selective bronchial obstruction in neonatal unilateral interstitial emphysema]. / Intérêt et limites de l'obstruction bronchique sélective dans l'emphysème interstitiel unilatéral néonatal.

BACKGROUND: Two methods of selective ventilation have been used for treating severe localized pulmonary emphysema in the neonates: controlateral selective intubation and selective bronchial obstruction. CASE REPORTS: Three neonates with acute respiratory distress required respiratory support that was complicated by development of severe localized pulmonary interstitial emphysema of the right lobe (two cases) and the middle lobe (one case). Selective bronchial obstruction with a Swann Ganz catheter SF was tentatively made: in one case, improvement was moderate and transitory, requiring middle lobectomy. The localized emphysema disappeared within 3 days in the two other cases but a localized emphysema appeared in the controlateral lung in one of them, requiring left inferior lobectomy because the ineffectiveness of selective intubation or selective obstruction. CONCLUSION: Selective bronchial obstruction may fail but this easy and well tolerated method should be tried in severe localized emphysema, specially in those patients who cannot be ventilated with high-frequency oscillation.