Regulatory T cells (Tregs) have been shown to be critical in the balance between autoimmunity and tolerance and have been implicated in several human autoimmune diseases. However, the small number of Tregs in peripheral blood limits their therapeutic potential. Therefore, we developed a protocol that would allow for the expansion of Tregs while retaining their suppressive activity. We isolated CD4+CD25 hi cells from human peripheral blood and expanded them in vitro in the presence of anti-CD3 and anti-CD28 magnetic Xcyte™Dynabeads® and high concentrations of exogenous Interleukin (IL)-2. Tregs were effectively expanded up to 200-fold while maintaining surface expression of CD25 and other markers of Tregs: CD62L, HLA-DR, CCR6, and FOXP3. The expanded Tregs suppressed proliferation and cytokine secretion of responder PBMCs in co-cultures stimulated with anti-CD3 or alloantigen. Treg expansion is a critical first step before consideration of Tregs as a therapeutic intervention in patients with autoimmune or graft-versus-host disease.

ABSTRACI' The aim of this study was to observe the effect of obesity on the plasma chromium profile and excretion after a glucose challenge in control subjects and noninsulin- dependent(NIDD)and insulin-dependent diabetics(IDD). All subjects were given 75 g glucose orally; serial blood and urine samples were collected for Cr analysis. Lean control subjects had significantly lower plasma Cr and insulin values than did obese control subjects at all times except zero (1 h, 12.69 ± 6.73 vs 22.31 ± 13.27 nmol/L, p < 0.020). No significant differences were seen between lean and obese NIDDS and IDDs. NIDDs taking drugs had higher Cr values than did lean control subjects (13.08 ± 0.58 vs 22.31 ± 5.00 nmol/L, p < 0.02). Cr concentra- tion of oral drugs was 22.4 ng/tablet and of the soluble insulins was 0.012 ± .003 ng/U. The lean IDDs excreted higher levels of Cr than did the control subjects; however, Cr excretion within individual groups was not found to be significantly different. The results suggest Cr metabolism is influenced by BMI in control subjects but not in diabetics. Am J C/in Nutr 1989;49:685-9.