Characterization of thymocyte subpopulations by enzymatic markers.

The activities of ecto-5'-nucleotidase (E5N), deoxyadenosine kinase (dAK) and deoxyguanosine kinase (dGK), were determined in thymocyte subpopulations, separated by peanut agglutinin (PNA). The activity of dAK in the PNA+ (agglutinated by PNA) thymocyte subpopulation was 2.5-fold that in the PNA- subpopulation. The activities of E5N and of dKG were found to be higher in the PNA- than in the PNA+ subpopulation by 15- and 4-fold, respectively. The activity of these enzymes can therefore be utilized to characterize the thymocyte subpopulation. In addition, since PNA+ cells are considered to be young immature precursors of the PNA- thymocytes, the activity of these enzymes may serve also as markers for the degree of maturation of the T cells.