Flow cytometric assessment of allopurinol susceptibility in Leishmania infantum promastigote

Background: Leishmaniasis is a major tropical and subtropical parasitic disease.Sodium stibogluconate, N-methyl -D-glucamine antimoniate, amphotericin B, pentamidine, and ketoconazole are drugs used to treat this disease.Some of these drugs cause severe adverse side effects and treatment failures are common.Allopurinol, a purine analog, has been used to treat leishmaniasis, alone or combined with the previously mentioned drugs.Low cost, ease of administration (oral), and lack of toxicity make allopurinol a particularly appealing candidate.Methods: The effect of allopurinol on Leishmania infantum (MCAN/ES/89/IPZ229/1/89, zymodeme MON1) wildtype promastigotes (wt-p229), and an altered form of these promastigotes (allo-p229) resulting from long term in vitro exposure to allopurinol, was determined by [ 3 H]thymidine incorporation assays and by diverse flow cytometric approaches.Results: Allopurinol arrested the proliferative capacity of wt-p229 promastigotes, reduced the proportion of viable cells, and decreased their total protein content.In contrast, allo-p229 promastigote proliferation was only slightly decelerated and the proportion of viable cells and the protein content were not affected by the allopurinol treatment. Conclusions:The flow cytometry approach allowed us to demonstrate differences in allopurinol susceptibility of the two promastigote forms, expanding the spectrum of flow cytometry applications in studies of parasite resistance.