Differences in the Cellular Immune Response during and after Treatment of Sudanese Patients with Post-kala-azar Dermal Leishmaniasis, and Possible Implications for Outcome

BackgroundThe host cellular immune response associated with two treatments for post-kala-azar dermal leishmaniasis (PKDL) - paromomycin plus miltefosine (Arm 1), and liposomal amphotericin B plus miltefosine (Arm 2) - was examined in Sudanese patients before treatment (D0), at the end of treatment (D42), and during the post-treatment period (D180).MethodsWhole blood samples were stimulated with soluble Leishmania antigen for 24 h (whole blood assay [WBA]) and the concentrations of Th1/Th2/Th17-associated cytokines, IP-10, PDL-1 and granzyme B were determined.ResultsThe Arm 1 treatment (98.2% cure rate) induced a Th1/Th2/Th17 response, while the Arm 2 treatment (80% cure rate) induced a Th1/Th2 response. Five Arm 2 patients relapsed and showed lower IFN-gamma, TNF and IL-1 beta concentrations at D0 than non-relapsers in this Arm. In patients with low-IFN-gamma-production at D0, Arm 1 treatment led to a better host immune response and clinical outcome than Arm 2 treatment.ConclusionsA Th1/Th2/Th17 response was associated with a higher cure rate. Patients with low IFN-gamma, TNF and IL-1 beta before treatment are more likely to relapse if they undergo Arm 2-type treatment. Determining IFN-gamma, TNF and IL-10 levels prior to treatment could help predict patients at higher risk of relapse/recovery from PKDL.Trial RegistrationClinicalTrials.gov NCT03399955, Registered 17 January 2018, https://clinicaltrials.gov/study/ NCT03399955. No blood biomarker can currently predict treatment outcome for patients with PKDL.The cellular response during treatment is key to overcoming leishmaniasis.Patients who relapsed showed low SLA-induced production of IFN-gamma, TNF and IL-1 beta.Treatment effectiveness was related to higher IFN-gamma production and absence of IL-10.PKDL treatment can be monitored and relapse predicted by the whole blood assay.