Results in two infants with the DiGeorge syndrome--effects of long-term TP5.

We treated two patients affected by DiGeorge syndrome with long-term administration of the synthetic thymic hormone thymopoietin (TP5). In both cases we obtained durable immunological reconstitution, starting as early as 2 weeks after beginning of TP5 treatment. High levels of circulating immature thymocytes and precursor T cells (defined by monoclonal antibodies OKT6, OKT9, and OKT10) were present prior to therapy, and they steadily decreased during the first few weeks of study. During the same time, phenotypically mature T lymphocytes (OKT3+ and OKT4+/OKT8+) markedly increased, thereafter remaining at near normal levels. OKT10+ cells appeared to rise again after 3 months of TP5 treatment. In vitro function of T cells, assessed by PHA stimulation, and in vivo cell-mediated immunity (skin tests with Candida) were normal at 3 and at 2 months, respectively, after initiation of therapy. No severe infection episodes were recorded and normal development was achieved. No side effect or adverse reaction occurred. In these two patients the other features of the DiGeorge syndrome were successfully treated by early cardiac surgery and vitamin D therapy. The immunological reconstitution, in absence of functioning thymus observed in these two cases, provides further evidence of the effectiveness of long-term treatment with thymic hormones--with maintenance of the improvement of cell-mediated immunity.