Different Patterns of Fluorescence in the Quantisation of anti-Leishmania Infantum Antibodies by Indirect Immuno-Fluorescent Antibody Test (IFAT) in the Serological Diagnosis of Canine Leishmaniasis

摘要

Although Indirect Immuno-Fluorescent Antibody Test (IFAT), performed employing “in house” prepared antigen, is considered by several authors as the golden standard for the quantisation of anti-leishmania antibodies in dogs, there is a lack of papers reporting a description of the different patterns of fluorescence that can be observed. An incorrect identification of patterns of fluorescence may be an important source of bias in the interpretation of results. Previous papers report different criteria to define as “positive” a specific pattern of fluorescence, namely: membrane fluorescence, homogeneous fluorescence of the body, or homogeneous fluorescence of the body plus flagellum. In this paper, we report a detailed description of preparation of slides and of the patterns of fluorescence that can be obtained employing “in house” prepared antigen. At least six main patterns of fluorescence may be observed: 1): homogeneous cytoplasmatic green fluorescence;2): membrane pattern, in which the fluorescence is mainly localized along the entire perimeter of the parasites;3): coarse-speckled cytoplasmatic fluorescence;4): flagellar pattern, in which the fluorescence is localized exclusively onto the flagellum;5): punctiform pattern, in which the fluorescence is localized exclusively at the basis of the flagellum;6): nuclear pattern, in which only the nucleus of the parasite shows a homogeneous green fluorescent. The significance of each pattern is discussed.