Elevated argininosuccinate synthetase activity in adult T leukemia cell lines

Argininosuccinate synthetase (ASS) is a ATP-dependent and rate-limiting enzyme of the urea cycle which catalyzes L-citrulline to L-arginine in combination with argininosuccinate lyase (ASL). We demonstrate here that (a) human normal T and B lymphocytes did not express ASS activity, (b) however, three adult T leukemia (ATL) cell lines tested here exhibited significant elevation of ASS activity, and (c) ASL activity remained relatively constant in normal lymphocytes and various leukemia cell lines. These results suggest that the ASS expression of peripheral blood lymphocytes is of value as a diagnostic marker of leukemia including ATL. The implication of these results is discussed.