Fig. 2.

Effects of P18 and P24 and of their respective iso-adenosines on CFC growth. CB MNC were incubated in the presence of various concentrations of P18 (filled triangles), P24 (filled squares), and the isoadenosine moiety derived from P18 (open triangles) and from P24 (open squares) by enzymatic (NPP plus CIP) digestion (see Supporting Materials and Methods). After 24 h, aliquots of cells (1-2 × 10⁴) were seeded in semisolid medium to allow for colony growth. Results are expressed as percentage of inhibition of colony growth compared with controls, which were incubated with the same dilution of chromatographic buffer as present in the HPLC-purified compounds. The IC₅₀ values were determined from the logarithmic regression curves (R ≥ 0.97). Results are the mean from at least three different experiments.