The acid phosphatase activity in lymphocytes with regard to the ontogenetic development of man.

In 120 healthy subjects aged from 1 day of life to 90 years the activity and intracellular localization of acid phosphatase (AP) in the peripheral blood lymphocytes has been evaluated by using semiquantitative cytochemical method (Barka and Anderson 1962). The long lasting stability of the lysosomal apparatus of lymphocytes during the ontogenetic development between the first day of life and the fifth decade of life has been stated. The stability was expressed by relatively constant number of lymphocytes containing intact AP-positive lysosomal granules. During the last decades of life between 66 and 90 year lymphocyte lysosomes are destabilized and numerous cells with cytoplasmatic diffusion of the enzyme can be observed. According to the author's opinion the above phenomenon corresponds to the aging of the lymphocyte system.