L-asparaginase and in vitro lymphocyte blastogenesis. Cell membrane alteration as possible mechanism of inhibitory effect

Lymphocytes which were incubated with Erwinia carotovaraL-asparaginase for only 1 hour were found to be markedly non-responsive to soluble antigens and moderately non-responsive to allogeneic cells or phytohaemagglutinin. When lymphocytes were exposed to antigen first, the inhibitory effect of L-asparaginase was markedly diminished, whereas exposure of lymphocytes to the enzyme prior to contact with antigen resulted in almost complete inhibition of blastogenesis. These observations suggest that L-asparaginase acts on the cell membrane causing impairment of antigen or mitogen binding, and that this is responsible for its inhibitory effect.