L-Glutaminase: Suppression of lymphocyte blastogenic responses in vitro

Continuous exposure to 0.1 international unit or more of Escherichia coli L-glutaminase inhibited responses of human lymphocytes to phytohemagglutinin, streptolysin O, and allogeneic leukocytes. Inhibition was completely reversed by removing the enzyme from the culture or adding L-glutamine but not L-asparagine. Cytoxicity did not occur. L-Glutaminase should be immunosuppressive in vivo.