Inhibition of Blastogenesis by Native and Polyethylene Glycol-Modified Asparaginases from Escherichia Coli and Vibrio Succinogenes

The in vitro blastogenic response of rat splenocytes to concana-valin A stimulation is inhibited by inclusion of asparaginase in the culture medium. The glutaminase-free asparaginase from Vibrio succinogenes is as potent an inhibitor as the Escherichia coli enzyme which has 2% glutaminase activity. The polyethylene glycol-modified forms of both enzymes are also inhibitory. We suggest that previously proposed explanations for the ability of asparaginases to inhibit blasto-genesis are not likely to be correct and propose that asparaginase interacts with a mitogenic factor.