Polyamine content and drug sensitivities of different clonal lines of Leishmania infantum promastigotes.

Two isolates (skin and lymph node) of Leishmania infantum obtained from a naturally infected dog were cloned and the free pools of polyamines for both complete isolates and clones were determined. Putrescine (Put) and spermidine (Spd) levels were highly variable among the lines studied, ranging from 0.89 to 2.1 nmol Spd/10(7) promastigotes. The Put/Spd ratio was also variable (1.54-0.51) and correlated with the cell growth of the lines studied. There were important differences in the clones' sensitivities to difluoromethylornithine (DFMO) and Berenil, with some of the clones being almost refractory to the inhibitory effect of 50 microM DFMO, whereas the growth of others was reduced by 60%; similar findings were obtained with 50 microM Berenil. L. infantum sensitivities to DFMO and Berenil were correlated and apparently related to the values for the Put/Spd index.