Peldesine (BCX 34) dihydrochloride is a potent, competitive, reversible, and orally active inhibitor of purine nucleoside phosphorylase (PNP), with IC50 values of 36 nM, 5 nM, and 32 nM against human, rat, and mouse red blood cell (RBC) PNP, respectively. Additionally, it inhibits T-cell proliferation with an IC50 of 800 nM, showing promise for research into cutaneous T-cell lymphoma, psoriasis, and HIV infection [1] [2] [3] [4].

Peldesine (BCX 34; 0-50 μM; 72 hours; Jurkat cells) effectively inhibits T-cell proliferation at concentrations below 10 μM when combined with 10 μM dGuo, without affecting B-cell proliferation. This action suggests Peldesine predominantly impacts a later phase of T-cell activation via an IL-2-independent mechanism, indicating its potential to selectively suppress T-cell immune responses. Additionally, Peldesine significantly inhibits human leukemia CCRF-CEM T-cell proliferation (IC 50 of 0.57 μM) in the presence of deoxyguanosine, without impacting rat or mouse T-cell proliferation at concentrations up to 30 μM. These findings highlight Peldesine's specific inhibitory action on certain T-cell lines under defined conditions.