The Number of MHC class Ⅱ Positive Splenic Antigen Presenting Cell in Babesia microti and Babesia rodhaini infected mice

Abstract

To elucidate helper T (Th) cell activation by the class Ⅱ major histocompatibility complex (MHC), Ia molecules, positive antigen presenting cells (APC), including macrophages and activating B cells, changes of the number of Ia positive APC in spleen cell were examined by flowcytometric analyses in Babesia microti and Bebesia rodhaini infected mice. The number of neither Ia positive macrophages nor Ia positive B cells showed significant difference between B. microti and B. rodhaini infected mice until day 9 after inoculation. However, the splenic Th cell developed IFN-γ Producing Th cell type 1 (Th1) in B. microti and IL-4 producing Th cell type 2 (Th2) in B. rodhaini infected mice. These results demonstrated that the proliferation of APC is not major factor for the differentiation of Th cell into Th1 or Th2 cell and suggested that some humoral factors regulate the differentiation in the early phase of infection with B. microti and B. rodhaini.