Lactic dehydrogenase and radiation-induced lymphoid leukaemia in mice.

The enzyme activity and the electrophoretic characteristics of lactic dehydrogenase (LDH) in the plasma and different tissues from the mice with radiation-induced lymphoid leukaemia were examined and compared with those obtained from the normal mice. The LDH activity was ab­ normally increased in the leukaemic plasma. A considerable elevation of the enzyme level was also found both in the leukaemic spleen and in the lymphocytes isolated from it, but not in the liver, kidney, heart and muscle. LDH isozyme patterns were obtained by agar-gel electrophoresis. Each tissue exhibited a characteristic distribution of LDH activity among the separated isozymes. Leukaemic plasma contained much more LDH-5 than normal plasma, showing the pat­ tern similar to that obtained from leukaemic spleen. Kidney and heart from leukaemic mice indi­ cated no difference in the LDH-patterns as compared with those from normal mice.