INHIBITION OF PURINE NUCLEOSIDE PHOSPHORYLASE-ACTIVITY AND OF T-CELL FUNCTION WITH ALLOPURINOL-RIBOSIDE

Allopurinol-riboside competitively inhibits the action of purine nucleoside phosphorylase on inosine in vitro with a Ki of 277 μmol. After simple incubation of allopurinol-riboside with PNP, allopurinol was not formed. Lymphocyte blastogenesis induced by PHA and Con A was significantly suppressed by allopurinol-riboside in a concentration-dependent manner. When LPS was used as a mitogen, the inhibition of allopurinol-riboside on lymphocyte proliferation was less marked. Humoral immunity was not suppressed by allopurinol-riboside. In contrast, cellular immunity was significantly suppressed by allopurinol-riboside in vivo. These results suggested that allopurinol-riboside is a drug which produces a model of PNP deficiency, and that it may be a useful inhibitor of cellular immunity. © 1979 Birkhäuser Verlag.