Leishmania infantum-specific IFN-? production in stimulated blood from cats living in areas where canine leishmaniosis is endemic

Priolo, Vito; Martínez-Orellana, Pamela; Pennisi, Maria Grazia; Masucci, Marisa; Prandi, David; Ippolito, Dorotea; Bruno, Federica; Castelli, Germano; Solano-Gallego, Laia

IFN-γ production after stimulation with ConA was obtained in almost all cats and it was not associated with any variable, including clinical status, retroviral infections or exposure to L. infantum. These findings are similar to data from studies of CanL [10, 28] . As expected, concentrations of ConA-IFN-γ were significantly higher than LSA-IFN-γ and they were positively correlated. Production of ConA-IFN-γ suggests non-specific T cell activation. Surprisingly, when considering cats exposed to L. infantum (i.e. positive to at least one the specific tests performed), sick individuals produced a significantly higher level of ConA compared to apparently healthy individuals. This finding is unusual, and it is difficult to when a significantly lower concentration is observed [10] . The prevalence of anti-L. infantum antibodies obtained in this study by combination of both IFAT and ELISA results was similar in the two regions with an approximate value of 20%. It is not easy, therefore, to explain the higher frequency and level of positivity of ELISA in Sicilian cats but these cats were more frequently found sick compared to Catalan cats ( Table 2 ). Previous studies conducted in Sicily were based on IFAT and, when the same cut-off was used, anti-L. infantum antibody prevalence ranged between 6.6-29% [19, [29] [30] [31] [32] . Conversely, only two studies evaluated anti-L. infantum antibody prevalence in Catalonia; they both used ELISA and antibody prevalence was 1.7 and 5.3%, respectively [14, 33] . However, as already reported, we found a positive correlation between ELISA and IFAT [21] .