Lymphocyte subset abnormalities in canine leishmaniasis.

Peripheral blood lymphocyte subpopulations were studied in 42 Leishmania infantum-infected dogs using flow cytometry. Twenty-two healthy dogs were used as a control group. Analysis of the B-cell populations showed a reduction in the number of CD21+ cells in all the infected dogs. On the other hand, the disease was found to be associated with a striking decrease in the number of CD21+ cells and of T-lymphocyte CD4+ cells in comparison with asymptomatic dogs and with healthy dogs. This study suggests that the dysimmunity which is observed with leishmaniasis may be linked to a reduced number of T-lymphocyte CD4+ cells.