682 THYMOSIN EFFECT IN PATIENTS WITH DIGEORGE SYNDROME

Abstract

The effect of thymosin on T-cell function was studied in 5 patients with DiGeorge Syndrome. Initially all had low numbers of T-cell rosettes(TCR), and decreased lymphocyte responses to phytohemagglutinin (PHA) and allogeneic cells (MLC). In 3 of 4 patients tested the %TCR was significantly increased above baseline values (2 became normal) when incubated in vitro with thymosin. MLC reactivity nearly doubled with in vitro thymosin incubation in 2 patients, although the stimulation index remained abnormal. While awaiting fetal thymus transplants 4 patients received in vivo thymosin therapy. After 2 wks at 1 mg/kg/day 1 patient demonstrated normal %TCR, PHA and MLC responses. A spontaneous recovery from immunodeficiency cannot be excluded. The other 3 patients had no change in their immunocompetence, although treatment periods were short. Thus, despite in vitro enahncement of cellular immune function, a consistent in vivo response to thymosin remains to be demonstrated in patients with DiGeorge Syndrome.