T cell-mediated suppression is an established phenomenon, but its unde
rlying mechanisms are obscure. An in vitro system was used to test the
possibility that anergic T cells can act as specific suppressor cells
. Anergic human T cells caused inhibition of antigen-specific and allo
specific T cell proliferation. In order for the inhibition to occur, t
he anergic T cells had to be specific for the same antigen-presenting
cells (APCs) as the T cells that were suppressed. The mechanism of thi
s suppression appears to be competition for the APC surface and for lo
cally produced interleukin-2.