Comparison of three assays for the evaluation of specific cellular immunity to Leishmania infantum in dogs

Cellular immune response to Leishmania plays a key role in canine leishmaniosis. However, there are few assays to evaluate this response in the dog. Here, we evaluated and compared three assays of specific cellular immune response to Leishmania infantum in dogs: the leishmanin skin test (LST), lymphocyte proliferation assay (LPA) and IFN-γ cytopathic effect inhibition bioassay (IFNB). Fifty-six healthy dogs from an endemic area for leishmaniosis on the island of Mallorca were studied. In all, 37 dogs showed a positive LST and 32 a positive IFNB, 24 were positive for both assays. The 17 dogs positive for LPA also gave positive results for either LST or IFNB, or both. These findings indicate that although LST is the method of choice, IFNB is a complementary test. Therefore, both assays should be performed and analyzed jointly. In comparison with LST and IFNB, LPA is much less sensitive, and yields many false negative results.