Changes in selected blood lymphocyte subpopulations in dogs administered with a soluble parasitic antigen (SPA) derived from a supernatant of 18S RNA-A and 18S RNA-B Babesia canis cell culture were investigated. The studies included 20 dogs divided into three groups: group I (n=8) - comprised of dogs receiving SPA twice, at 3 week intervals; group II (n=5) - nonvaccinated control dogs, and group III (n=7) - dogs vaccinated twice with a commercial B. canis vaccine. Cytometric analysis revealed that vaccination with SPA derived from B. canis culture had similar effects to the vaccination with a commercial vaccine. The vaccination lowered the percentage of T lymphocytes (CD3+), T helper cells (CD4+), cytotoxic/supressor T cells (CD8+), B lymphocytes (CD21+), and MHC II lymphocytes in the blood in comparison to non-vaccinated dogs. Statistical analysis of the results demonstrated that mean values of the tested parameters at each stage of the study were similar in groups I and III and significantly higher in group II. The lowered level of the lymphocyte subpopulations in groups I and III persisted during the whole period of the study. The results presented that SPA has immunosuppressive effect in the first period after being administrated.
