EFFECTS OF PARTIALLY THIOLATED POLYCYTIDYLIC ACID ON THE CLONOGENICITY OF MURINE LEUKEMIC STEM-CELLS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 39  (8) , 3163-3166
Abstract
The effect of partially thiolated polycytidylic acid (MPC) on the colony-forming ability of the progenitor cells (CFUC) of RF/Un leukemic mice was investigated using the plasma clot method to study the mode of action of the modified polynucleotide. MPC inhibited the CFUC in a dose-dependent and time-dependent manner. Once a maximum level of inhibition of CFUC (.apprx. 40%) was observed, no further inhibition occurred whether the concentration of MPC was increased or whether the duration of incubation was lengthened. High-specific-activity [3H]thymidine, an S-phase-specific agent, showed a similar inhibition profile on the CFUC as did MPC. When MPC and high-specific-activity [3H]thymidine were incubated together with the bone marrow cells, there was no additive or synergistic inhibitory effect on the CFUC. Thus, MPC is an S-phase-specific agent. When injected i.v. into the mice, MPC decreased the number of CFUC of the bone marrow and the spleen significantly.