) Their BM aspiration was performed as a part of routine diagnostic evaluation. Subsequently, their BM found to be normal haematologically. Flowcytometry based phenotyping using specific antibodies against CD3 (PE; BD Pharmingen, San Diego,

CA, USA), CD161 (Cy5PE; BD Pharmingen) and Vα24 (FITC, Dako Coulter, Glostrup, Denmark)/Vβ11 (FITC; Serotec, Kidlington, UK)/iNKT (FITC; BD Pharmingen) showed an increase in the frequency of iNKT (CD3+ CD161+ Vα24/Vβ11+) cells GSK126 order in blood (n = 28; percent mean ± SD, 1·35 ± 1·66) of freshly diagnosed patients compared with that of healthy controls (n = 17; percent mean ± SD, 0·34 ± 0·24) (Figure 1a,b,e). iNKT cells are also enriched in the BM of patients with VL (n = 17; percent mean ± SD, 1·19 ± 1·17) as compared with NBM (n = 9; percent mean ± S.D., 0·34 ± 0·13) (Figure 1c,d,f). The enrichment of iNKT cells was disease specific, as their frequency is significantly buy APO866 decreased after successful therapy (post-therapy) (Figure 1e,f). To observe the frequency of CD1d reactive cells, we mixed αGalcer with CD1d dimer (in 40× molar excess ratio). The mononuclear cells derived from blood and BM were stained with αGalcer-loaded CD1d dimer (Supporting information Figure S1). Frequency of αGalcer-loaded CD1d-reactive

NKT cells remains unaltered in blood and BM, as compared with blood of HCs (Figure 1g,h). In our effort to enumerate the parasite-specific CD1d reactive cells, we loaded CD1d dimer

with LPG (Supporting information Figure S2). The frequency of LPG-loaded CD1d+ NKT cells derived from BM ranges from 0·2 to 0·7% in a limited number of patients (n = 5) BIBF1120 (Figure 1i). In context to human VL, it would also be interesting to observe the response of iNKT cells against various lipid antigens of L. donovani, particularly LPG and GPIL. Reports suggest that L. donovani-infected kupffer cell activates iNKT cells (10) and activation of iNKT by αGalcer augments the disease pathology among L. donovani-infected mice (11). Our preliminary finding in a limited number of patients (n = 4) suggests that iNKT cells produce both IFN-γ as well as IL-4 in response to polyclonal stimulation (Supporting information Figure S3). To add further, αGalcer stimulates the production of IFN-γ and IL-4 by iNKT cells (6). Developing an analogue of αGalcer, which selectively produce either IFN-γ or IL-4, will be appropriate in tuning the right kind of iNKT cells. Recent development in human-specific thioglycoside analogue of αGalcer, which triggers the production of IL-12 and IL-10 by iNKT cells (12), suggests it as a candidate vaccine of immense potential. Identification of a pro-inflammatory IL-17 producing subset of iNKT cells inflates its potential under diseased condition (13). Triggering iNKT cells and thus modulating immune response among patients with VL might result in favour of host depending on their capacity to produce IFN-γ and IL-17.