N-acetyl-beta-glucosaminidase of lymphocytes in the premature infant with special reference to the fetal development of the lysosomas apparatus.

N-acetyl-beta-glucosaminidase activity was determined in peripheral blood lymphocytes by means of Hayashi's cytochemical method in 50 premature infants born between the 21st and 37th weeks of gestation. The lymphocytes exhibited three types of enzymatic cytochemical reaction, i.e. granular, diffuse and mixed (both granular and diffuse). The total count of enzyme-positive lymphocytes was significantly lower in the group of premature infants born between the 21st and 28th weeks of gestation as compared with those born later. This difference was due to the smaller numbers of enzyme-positive lymphocytes with granular reaction type in the group of more immature infants. The formation of enzyme-positive lysosomal granules within the lymphocyte cytoplasm during the last months of fetal development has been suggested and the relationship between the enzymatic equipment of lymphocyte lysosomes and immune response discussed.