Determination of CD4+ and CD8+ T cells in the peripheral blood of dogs with leishmaniosis before and after prolonged allopurinol monotherapy.

Canine leishmaniosis (CL) is a common systemic parasitic disease that is endemic in many Mediterranean countries including Greece. The immune reaction to the parasite is critical to the outcome of the infection and the response to treatment. Some studies have shown a reduction of circulating CD4+ T cells and of the CD4+/CD8+ ratio in dogs with CL and these changes normalised following treatment with meglumine antimoniate or amphotericin B. Allopurinol is used as a monotherapy for the chronic treatment of CL. The aim of the present study was to determine the circulating CD4+ and CD8+ T lymphocyte numbers and the CD4+/CD8+ ratio in 19 dogs diagnosed with CL before and after prolonged allopurinol monotherapy (18 months). A significant decrease in circulating CD4+ T cells was observed in dogs with CL before treatment. Prolonged allopurinol monotherapy improved the number of circulating CD4+ T cells, but did not restore their number to within the normal range.