Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Antigen-presenting cells limit T cell proliferation by degrading tryptophan. Macrophages that have been cultivated in the presence of M-CSF can suppress the proliferation of activated T cells. This inhibition results from the tryptophan-degrading activity of the intracellular enzyme IDO. T cells are thus limited for tryptophan, and proliferation is blocked in the G1 stage of the cell cycle.
