Flow cytometric assessment of allopurinol susceptibility in Leishmania infantum promastigote

Background: Leishmaniasis is a major tropical and subtropical parasitic dis ease. Sodium stibogluconate, N-methyl-D-grucamine antimoniate, amphotericin B, pentamidine, and ketoconazole are drugs used to treat this disease. Som e of these drugs cause severe adverse side effects and treatment failures a re common. Allopurinol, a purine analog, has been used to treat leishmanias is, alone or combined with the previously mentioned drugs. Low cost, ease o f administration (oral), and lack of toxicity make allopurinol a particular ly appealing candidate. Methods: The effect of allopurinol on Leishmania infantum (MCAN/ES/83/IPZ22 9/1/89, zymodeme MON1) wildtype promastigotes (wt-P229), and an altered for m of these promastigotes (allo-p229) resulting from long term in vitro expo sure to allopurinol, was determined by [H-3]-thymidine incorporation assays and by diverse flow cytometric approaches. Results: Allopurinol arrested the proliferative capacity of wt-p229 promast igotes, reduced the proportion of viable cells, and decreased their total p rotein content. In contrast, allo-p229 promastigote proliferation was' only slightly decelerated and the proportion of viable cells and the protein co ntent were not affected by the allopurinol treatment. Conclusions: The flow cytometry approach allowed us to demonstrate differen ces in allopurinol susceptibility of the two promastigote forms, expanding the spectrum of flow cytometry applications in studies of parasite resistan ce. (C) 2000 Wiley-Liss, Inc.