Demonstration of Leishmania specific cell mediated and humoral immunity in asymptomatic dogs.

An ELISA and a lymphocyte proliferation assay were used for the detection of anti-Leishmania antibodies and parasite specific cellular immunity respectively in a preliminary study of canine leishmaniasis in Oporto, Portugal. A high rate of infection was found considering the comparatively small group sampled. Of 34 dogs examined two had anti-leishmanial antibodies but their lymphocytes did not proliferate in the presence of Leishmania infantum. Conversely two dogs demonstrated antigen specific lymphocyte proliferation in the absence of any detectable anti-parasite antibodies. To our knowledge this is the first time that cellular immunity and presumably resistance of dogs to leishmanial infection has been demonstrated. These results suggest that there may be a spectrum of canine leishmaniasis similar to that observed in the human disease.