Figure 2.

Inhibition of PNP by Imm-H selectively prevents proliferation of malignant T cells. Human T cell leukemia cell lines CCRF-CEM (CEM) and MOLT-4, the human B cell leukemia line BL2, and the colon carcinoma line GEO were incubated for 3 days in the presence of 20 μ M dGuo and Imm-H at the indicated concentrations. Proliferation was determined by WST-1 activity (A) or by [5⁻³ [H]thymidine incorporation (B). Cell proliferation was expressed as the percent of control cell growth (see Materials and Methods). In C, CCRF-CEM cells cultured in the absence of dGuo or with added dCyd were protected from the inhibitory effects of Imm-H. Lines labeled “Imm-H”, “dGuo, Imm-H”, and “dGuo, Imm-H, dCyd” represented cells exposed to 10 μM Imm-H, 20 μM dGuo, and Imm-H, dGuo with Imm-H, and 20 μM dCyd, respectively.