Potential Role of Neutrophil-Platelet Interaction in Increased Susceptibility to Infection of Patients with Down Syndrome.

OBJECTIVE: Recurrent infection in Down syndrome (DS) has been previously documented; the potential role of platelets and neutrophil-platelet interaction has not been addressed in previous studies. PATIENTS AND METHODS: Using flow cytometry, we evaluated CD40 and CD18 expression as activation markers for neutrophils and CD62p as an activation marker for platelets, before and after lipopolysaccharide (LPS) stimulation, in 34 patients with DS and 39 control patients. RESULTS: Markers were evaluated as percentage of positivity, mean fluorescent intensity (MFI), and activation index (MFI after stimulation/MFI before stimulation). Patients showed a significantly lower CD40 MFI (P = .019) after LPS stimulation, a lower CD62p percentage before and after LPS stimulation (P = .013 and P = .029), and a higher CD62p MFI (P = .011) after LPS stimulation. Patients showed a lower activation index for CD40 and CD18 (P ≤ .001) but not for CD62p (P = .338). Dysfunctional efficiency in neutrophils and in the neutrophil-platelet interaction could not be correlated to infection. CONCLUSION: A consensus on a scoring system for infection is needed for an objective evaluation of correlation to infection.

Sex Chromosome Mosaicism in the Gonads of DSD Patients: A Karyotype/Phenotype Correlation.

Sex chromosome mosaicism results in a large clinical spectrum of disorders of sexual development (DSD). The percentage of 45,X cells in the developing gonad plays a major role in sex determination. However, few reports on the gonadal mosaic status have been published, and the phenotype is usually correlated with peripheral lymphocyte karyotypes, which makes the phenotype prediction imprecise. This study was conducted on 7 Egyptian DSD patients to demonstrate the effect of sex chromosome constitution of both blood lymphocytes and gonadal tissues on the phenotypic manifestations. Conventional cytogenetic and FISH analyses of blood lymphocytes were conducted, and laparoscopy with gonadal biopsy was performed for histopathologic examination and FISH analysis. Gonosomal mosaicism was detected in 3 patients who had a non-mosaic chromosome pattern in blood lymphocytes. Two patients showed the same type of sex chromosome mosaicism in both the blood and gonadal tissues but with different distributions. Two other patients revealed a non-mosaic pattern in both tissues. The present study elucidates the importance of examining sex chromosome mosaicism in gonadal tissues of DSD patients and highlights the critical role of 45,X mosaicism which can lead to serious effects during early gonadal organogenesis.