In vitro activity of anti-leishmanial drugs against Leishmania donovani is host cell dependent.
OBJECTIVE
To evaluate the in vitro activity of anti-leishmanial drugs against intracellular Leishmania donovani amastigotes in different types of macrophages.


METHODS
Mouse peritoneal macrophages (PEMs), mouse bone marrow-derived macrophages (BMMPhi), human peripheral blood monocyte-derived macrophages (PBM Phi) and differentiated THP-1 cells were infected with L. donovani. Cultures were incubated with sodium stibogluconate, amphotericin B deoxycholate (Fungizone), miltefosine or paromomycin sulphate over six concentrations in 3-fold serial dilutions for 5 days. Analysis was based on percentage inhibition of infected macrophages and EC(50)/EC(90) values estimated using sigmoidal curve-fitting.


RESULTS
The rank order of drug activity was the same in the different macrophage populations: amphotericin B > miltefosine > sodium stibogluconate > paromomycin. However, significant (P < 0.05) differences were observed between populations. Amphotericin B was more active in PEMs and BMM Phi (EC(50) 0.02-0.06 microM) compared with PBM Phi and differentiated THP-1 cells (EC(50) 0.08-0.40 microM) and miltefosine was more active in PBM Phi (EC(50) 0.16-0.74 microM) compared with PEMs and BMM Phi (EC(50) 2.60-7.67 microM). Sodium stibogluconate displayed highest activity in PBM Phi (EC(50) 1.38-1.89 microg Sb(v)/mL), followed by PEMs (EC(50) 21.75-27.79 microg Sb(v)/mL) and BMM Phi and differentiated THP-1 cells (EC(50) 28.96-112.77 microg Sb(v)/mL). Paromomycin showed highest activity in PBM Phi (EC(50) 80.03-104.38 microM) and PEMs (EC(50) 75.42-201.63 microM).


CONCLUSIONS
In vitro activity of anti-leishmanial drugs is host cell dependent. This has implications for: (i) the evaluation of in vitro drug activity; (ii) the evaluation of drug susceptibility of clinical isolates; and (iii) the standardization of anti-leishmanial drug assays.
Seifert
Karin
K
London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK. karin.seifert@lshtm.ac.uk
Escobar
Patricia
P
Croft
Simon L
SL
D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007893:Leishmania donovani / Q000187:drug effects*; D008264:Macrophages / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C
D000981:Antiprotozoal Agents