The role of PNP enzyme in autologous rosette-forming cells.

Since purine nucleoside phosphorylase has been associated with suppressor function in lymphocytes, enzyme activities were studied in autologous rosette-forming cells, a subset showing suppressor properties. Levels of this enzyme were higher in these cells than in other T cells. Con A induction of autologous red cell receptors and suppressor activity of T cells were both inhibited in dose-dependent fashion by Formycin B, a well known inhibitor of purine nucleoside phosphorylase. Inhibition of autologous rosette-forming cells was obtained after pulse treatment of cells with Formycin B for as little as 1 hr, whereas cell proliferation was only inhibited when Formycin B was present throughout culture; this confirms the independence of cell proliferation, and development of red cell receptors and suppressor activity. This study indicates a crucial role for purine nucleoside phosphorylase enzyme in induction of T cell suppressor activity.