RESUMEN
Children with Down syndrome [DS] have an increased rate of infection and it has been proposed that this is secondary to derangements of the immune system. Multiple immunologic disturbances were commonly observed in individuals with DS including abnormal proportions of peripheral lymphocytes subsets, cellular dysfunction and others. The present study was conducted on 20 children with Down syndrome. Sex distribution was 9 males to 11 females [1: 1.2] with age ranging from 1 month to 11 years [average 25.9 +/- 31.7 months]. Control group of 15 healthy children matched for age and sex were included. Karyotype by a standard technique, evaluation of the immune system by flow cytometry and estimation of serum cytokines [interleukin-1 Beta [IL-1Beta], interleukln-2 [lL-2] and tumour necrosis factor alpha [TNF-alpha]] were carried out. A Significant decrease of the absolute number of circulating lymphocytes, a marked significant decrease of B-lymphocytes and drarratic modifications of the T-cell subsets were observed. T-cell subpopulation studies revealed marked decrease in CD4+ subpopulation has been documented with inverted CD4/CD8 ratio, whereas CD8+ cells increased significantly in percentage. A derangement of cells bearing markers associated with natural killing [NK] activity such as CD19+ and CD56+ was observed. Among the most important alterations are the presence of a high number of CD56+ lymphocytes and significantly high percent of CD56+ CD8+ T cells. Regarding cytokine production, it was found that serum IL-2 levels were significantly decreased in DS children compared to the control group and its production was correlated inversely with age. On the other hand; lL-1Beta and TNF-alpha levels in DS Children showed no significant difference compared to normal subjects. We concluded that thymic alterations and molecular abnormalities due to gene over-expression of loci located on Chromosome 21 could be involved. On the other hand, the increased percent of CD56+ CD8+ T cells; as potent antitumour immunity; is emphasizing how rare are solid tumours in DS patients