Journal of Mental Deficiency Research, 1988, 32, 169-181 Oral zinc supplementation in Down's syndrome: restoration of thymic endocrine activity and of some immune defects C. FRANCESCHI,' M. CHIRICOLO,^ F. LICASTRO/ M. ZANNOTTI,' M. MASI,* E. MOCCHEGIANI^ AND N. FABRIS^- ^ 'Cattedra di Immunohgiay Istituio di Patologia Generale, Universita' di Modena, Modena, ~Dipartimento di Patologia Sperimentale, ^Istituto di Istologia ed Emhriologia Generale and '^Centro di Immunologia e Allergologia Pediatrica, htituto di Clinica Pediatrica, Universita' di Bologna, Bologna, ^Centro di Immunologia, Dipartimento Ricercke, htituto Nazionale di Ricovero e Cura per Anziani (INRCA), Ancona, and ^Dipartimento di Farmacologia, Universita' di Pavia, Pavia, Italy ABSTRACT. Eighteen non-institutionalized Down's syndrome (DS) children (mean age: 70110/12 years) with a history of respiratory tract, auditory and skin infections, fow plasma levels of a nonapeptide thymic hormone, i.e. Serum Thymic Factor (STF), high plasma levels of inactive zinc-unbound STF molecules, and reduced absolute number of circulating T-lymphocytes, were given an oral non-pharmacological supplementation of zinc sulphate (1 mg Zn ' * /kg body weight/day for 2 months; two cycles, 10 months apart) and monitored immunologically before and after each cycle. A dramatic increase of plasma STF level and concomitantly an almost complete disappearance of inactive STF molecules was observed after each cycle. The absolute number of circulating T-lymphocytes was significantly increased by zinc treatment. The marginal zinc deficiency was also corrected without any appreciable influence on copper plasma levels. A reduction of recurrent infections and an improvement in school attendance after zinc supplementation were recorded. These beneficial effects of zinc supplementation were also noted in those DS children who did not show an apparent zinc deficiency, as assessed by measuring zinc plasma level. The reduced number of circulating B lymphocytes and the impaired lymphocyte responsiveness to phytohaemaggluiinin and concanavalin A were not restored. On the whole, these findings suggest that there exists a defect in the bio-availability and/or in the utilization of zinc in DS. This alteration., of unknown origin, can be underestimated on the simple basis of the zinc plasma level and can be corrected with moderate nutritional zinc supplementation. INTRODUCTION Trace elements such as zinc are known to influence the efficiency of the immune system both in animals and in man (Bach, 1981; Chandra, 1983). Young animals and humans deprived of adequate amounts of dietary zinc exhibited generalized lymphoid hypoplasia, rapid thymic atrophy, decreased production of thymic hormones, impaired lymphocyte proliferative capability after phytomitogen stimulation, and Correspondence: Professor Claudio Franceschi, htituto di Patologia Generale, Facolta' di Medidna e Chirurgioi Universita' di Modena, Via Campi 287, 41100 Modena, Italy 169