Interference by platelets in the electrophoretic determination of enolase isoenzymes in plasma

Serum and plasma gave different electrophoretic patterns when enolase isoenzymes were evaluated by electrophoresis on cellulose acetate. Plasma isoenzyme bands were more intense, and there was an additional one (band P) that was not present in serum. We show that, under the conditions of electrophoresis, some of the residual platelets in the plasma are ruptured, releasing intracellular enolases and consequently leading to intensification of the isoenzyme bands. The band P originated from the remaining unruptured platelets. Thus plasma samples must be platelet-free for determination of enolase isoenzyme to be reliable.