Inmunodeficiencias

Acta Pædiatrica ISSN 0803–5253

REGULAR ARTICLE

Immunological patterns in young children with Down syndrome: is there a temporal trend?
Guido Cocchi (guido.cocchi@unibo.it), Maura Mastrocola, Marilu’ Capelli, Annalisa Bastelli, Francesca Vitali, Luigi Corvaglia
Neonatology and Preventive Paediatric Department, University of Bologna, Bologna, Italy

Keywords Down syndrome,Immunoglobulins, Lymphocyte subpopulations, Temporal trend, Zinc Correspondence Guido Cocchi, Neonatology and Preventive Paediatric Department, University of Bologna, Via Massarenti, 11 40138 Bologna, Italy. Tel/Fax: +39 051 342754 | Email: guido.cocchi@unibo.it Received 19 April 2007; revised 20 June 2007; accepted 28 June 2007. DOI:10.1111/j.1651-2227.2007.00459.x

Abstract Down syndrome is associated withan increased susceptibility to infections due to a deficiency of both specific and nonspecific immunity. Aim: The aim of the study was to analyze the temporal trends, if any, of some variables related to the immunological status of children affected by Down syndrome. Methods: Heparinized blood samples were obtained by venipuncture in 30 children with Down syndrome, who were regularly followed in ourdepartment and analyzed for hematologic values, lymphocyte subpopulations, immunoglobulin dosage and zinc level. Results were compared with those of the normal population. Results: In the first 5 years of life, we observed a progressive decrease in the medium values of lymphocytes, CD4+ and plasma zinc levels, and an increase in CD8+ , immunoglobulin A, immunoglobulin G, immunoglobulin M and naturalkiller, but generally without exceeding the interval of normality. Conclusions: In Down syndrome children, the immune cellular status is similar to the normal population as far as white blood cell, lymphocyte, CD4+ , CD8+ , natural killer and immunoglobulins are concerned. Plasma level of zinc is normal from birth until 5 years but with a temporal trend of progressive reduction. This observationsupports the hypothesis that a pharmacological supplementation may be necessary in Down syndrome children only after 5 years of age.

INTRODUCTION Down syndrome (DS) is the most commonly occurring chromosomal abnormality characterized by the presence of an extra copy of chromosome 21 (1). Children with DS have an increased susceptibility to multiorgan diseases, such as cardiovascular andgastrointestinal diseases (2), endocrine disorders, immune defects (3), autoimmune phenomena and malignancies. The increased susceptibility to infections, due to the deficiency of the immune system, has been well known for many years (4). The immunological defects include both specific and nonspecific immunity (5); however, the basis of the immune defects is still unclear. The human immune systemundergoes a process of functional development during the first years of life; therefore the relative and absolute number of lymphocyte (L) subsets, the percentage of CD8+ T and CD4+ T cells, white blood cells (WBC) and natural killer cells (NK) vary during childhood (6–8). A critical point is to understand why DS children show such a high frequency of immunodeficiency. Nespoli et al. documented a normalproportion of CD4+ T cells, but a marked imbalance in the CD4+ subpopulations, whereas the percentage of suppressor-cytotoxic CD8+ lymphocytes is markedly increased (3). On the contrary Corsi et al. showed that peripheral CD4+ T cells were lower in children with

DS, whereas mean values of cytotoxic CD8+ T cells were comparable with those from healthy children (9). Some studies show that somemicronutrients, in particular zinc, play an important role in the immunologic system (10). Murray et al. demonstrated that low levels of zinc can decrease the number of T cells and alter blood cell functions (11). Other authors say that zinc deficiency affects humoral immunity: recently Romano et al. found some antibody deficiency disorders in DS children (10). Bjorkstein et al. reported that...