Cytokine Release Assays as Tests for Exposure to Leishmania, and for Confirming Cure from Leishmaniasis, in Solid Organ Transplant Recipients

Spain has one of the world's largest pools of organ donors and is a global leader in terms of the number of transplants it performs. The current outbreak of leishmaniasis in Fuenlabrada (in the southwest of the region of Madrid, Spain) has involved 600 clinical cases since late 2009 (prevalence 0.2%). It may therefore be wise to monitor the town's transplanted population for Leishmania infantum; its members are immunosuppressed and at greater risk of infection and relapse following treatment. The present work examines the use of cytokine release assays to determine the prevalence of Leishmania infection in this population, and to confirm recovery following treatment for visceral leishmaniasis (VL). The humoral and cellular immune responses to L. infantum were characterized in 63 solid organ transplant (SOT) recipients from Fuenlabrada, 57 of whom reported no previous episode of VL (NVL subjects), and six of whom had been cured of VL (CVL subjects). Seventeen subjects (12 NVL and 5 CVL) showed a patent lymphoproliferative response to soluble Leishmania antigen (SLA). Stimulation of peripheral blood mononuclear cell cultures and of whole blood with SLA led to the production of different combinations of cytokines that might serve to confirm Leishmania infection or recovery from VL and help prevent cured patients from relapsing into this serious condition.We gratefully acknowledge the financial support of WHO via the APW-2012/271093 project and of the Instituto de Salud Carlos III via the Tropical Diseases Research Network (RICET RD12/0018/0003 and RD12/0018/0008) (URL) (www.ricet.es/en/) and via ISCIII-AES project Impact of leishmaniasis outbreak in the southwest of Madrid in the immunosuppressed population (PI13/00440). EC was supported by a research contract funded via VII PN I+D+I 2013-2016 and FEDER Funds (RICET RD12/0018/0003). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S