Release of beta-hexosaminidase after administration of different agents affecting the reticuloendothelial system. An...

Plasma levels of a lysosomal enzyme, beta-hexosaminidase (beta-N-acetylglucosaminidase, EC 3.2.1.30) were studied in Wistar rats after administration of 99mTc -sulfur colloid, 198Au colloid, gelatine (Haemaccel), alcohol, methylpalmitate and zymosan. The activity of beta-hexosaminidase was increased 10, 30 and 60 min after the zymosan injection. After 24 and 48 h, enzyme levels had returned to those at outset. The transient release of beta-hexosaminidase probably occurred only during the phagocytosis of zymosan which was evaluated by histological examination of lung, liver and spleen. After the injection of all other agents tested, no significant aberration of beta-hexosaminidase levels was seen. Activity distribution of the radio-labeled colloids revealed differences in organ uptake which were attributed to a difference in colloid particle size. Although the colloids tested have been used extensively for determination of reticuloendothelial function and histological studies suggest phagocytosis of the particles, their administration did not affect plasma beta-hexosaminidase levels. Since lysosomal enzymes are cleared from the blood predominantly by liver macrophages, the primary location of particle phagocytosis may explain the present findings.