CD28 and infection: In the target population, eosinophils (Siglec-F+ cells) demonstrated several significant changes upon infection with T. canis as follows: CD28, MHC-II, and CD69 expressions are upregulated, while CD86 is downregulated in the peripheral blood; CD80 and CD69 molecules are downregulated in the spleen; MHC-II and CD80 molecules are downregulated in the bone marrow of mice infected with the parasite when compared with the control group.