Thymic hormone dependent immunodeficiency in an infant with partial trisomy of chromosome 22.

An infant with partial trisomy 22 syndrome and recurrent infections showed severe cellular immunodeficiency and serum IgG reduction. A marked increase of E-RFCs was observed after in vitro incubation of peripheral blood lymphocytes with thymostimulin (TS), a calf thymic extract. The treatment with TS resulted in reduction of infections, correction of cellular immunodeficiency and increase of IgG levels. Such a primary thymic hormone dependent immunodeficiency may be due to an altered development of branchial arches, commonly present in trisomy 22 syndrome. The same pathogenetic mechanism may account for thymus dysplasia observed in other chromosomal syndromes.