Whole Blood Stimulation Assay as a Treatment Outcome Monitoring Tool for VL Patients in Ethiopia: A Pilot Evaluation

Development of a Simple IFN-γ Release Whole Blood Assay for the Assessment of Leishmania infantum Specific Cellular Immunity in Dogs

Canine leishmaniosis (CanL) is a zoonotic disease caused by Leishmania infantum, where increased interferon-gamma (IFN-γ) levels are associated with controlling the infection and mild to moderate disease. Therefore, monitoring IFN-γ concentrations is essential for monitoring the immune responses in CanL. This study compared a faster, cost-effective IFN-γ release whole blood assay in tubes (WBA-T) with a standardized version (WBA-S) in 41 dogs at different states of L. infantum infection. WBA-T was performed at 24, 48, and 72 h of incubation with three conditions: blood, blood with L. infantum-soluble antigen (LSA), and blood with mitogen ConA. WBA-S was performed in plates, with blood diluted and incubated for five days using the same conditions. Supernatants (WBA-S) or plasma (WBA-T) were harvested for IFN-γ measurement by ELISA. No significant differences were observed in terms of IFN-γ concentration between WBA-T and WBA-S under LSA conditions. However, the 48 h incubation period during WBA-T showed the highest median of IFN-γ concentration compared to other incubation periods and WBA-S. The IFN-γ concentrations under ConA stimulation in WBA-S were significantly higher than in WBA-T at all incubation times studied. In conclusion, WBA-T stimulated with LSA at 48 h incubation time was shown to be the most appropriate for assessing IFN-γ production.

Evaluation of Chemokines MIG and IP-10 as Immunological Biomarkers of Human Visceral Leishmaniasis: A Systematic Review

Visceral leishmaniasis (VL) is a neglected tropical disease that is potentially fatal when untreated. Current diagnostic methods have limitations that contribute to ongoing transmission and poor prognosis. Thus, new tests are needed to provide quick, accurate diagnoses and evaluate clinical progression and treatment efficacy. The monokine induced by interferon-gamma (MIG) and interferon-gamma-inducible protein 10 (IP-10) has been associated with the host susceptibility to VL with potential diagnostic and prognostic purposes. We performed a systematic review using four search databases (Scopus, PubMed, Web of Science, and MEDLINE) to identify studies assessing MIG and IP-10 as potential biomarkers in patients with VL across various clinical conditions. A total of 13 studies were potentially eligible and included in this review. The articles, in general, reveal that the chemokines MIG and IP-10 are elevated in response to infection by Leishmania spp., acting on the host's resistance to the development of the disease. They are associated with asymptomatic conditions and after VL treatment, and this relationship can be observed in both immunocompetent and immunocompromised individuals. Consequently, these chemokines hold relevance in the diagnoses and appropriate management of individuals with VL.

An exploratory analysis of C-X-C motif chemokine ligand 10 as a new biomarker of asymptomatic Leishmania infantum infection in Solid-Organ Transplant Recipients

OBJECTIVE

Sensitive and less laborious assays are needed to detect asymptomatic Leishmania among solid organ transplant (SOT) recipients. Using SLA-stimulated plasma from SOT recipients living where an outbreak of Leishmania infantum occurred, we examined potential biomarkers to identify asymptomatic Leishmania infections.

METHODS

Concentrations of cytokines/chemokines in plasma from whole blood stimulated with specific Leishmania antigen (SLA) were compared against infection status as determined by a currently used cell proliferation assay.

RESULTS

Twenty-six percent (13/50) of the SOT recipients had a cell proliferation assay (CPA) indicating asymptomatic infection, and showed higher processed plasma C-X-C motif chemokine ligand 10 (CXCL10 or IP-10) concentrations than did non-infected subjects (median 2272.0 pg/ml [IQR-1570-2772] vs. 18.2 pg/ml [IQR 1-150.1]; p<0.0001). CXCL10 showed a sensitivity of 93% and a specificity of 95% compared to CPA. In addition, we demonstrated that the number of asymptomatic infections detected using CXCL10, decreased with distance from a park at the centre of the mentioned outbreak.

CONCLUSION

CXCL10 in plasma from SLA-stimulated blood could be a robust biomarker of asymptomatic L. infantum infection in solid organ transplant recipients.