Abstract: Objective To investigate the relation between activation of B-cells and maturation of dendritic cells(DC) in the spleens of ICR mice infected with chloroquine-resistant(RC) or chloroquine-sensitive(N) strain of Plasmodium berghei. Methods Spleens were taken after the mice were infected with N or RC strains of P. berghei and attained certain degree of parasitemia. Changes of B-cells and DCs were examined by pathological method, immunohistochemistry and immunofluorescence methods, transmission electron microscopy (TEM) and flow cytometry technology. Results Proliferation of white pulps in the spleen of mice infected with RC strain was found as compared to that with N strain. The percentage of cluster of differentiation(CD) 45R/B220, CD19 cells increased in the spleen cells, number of medium and small lymphocytes increased in the germinal centers, the immature and mature plasma cells also increased in the red pulps of spleen in RC strain-infected mice. On the contrary, in the N strain-infected mice spleen, the white pulps were reduced and the red pulps were filled with parasite-infected red blood cells; less small lymphocytes, immature and mature plasma cells were observed in red pulps. The number of CD11c DCs increased, especially in the periarteriolar lymphoid sheath, T cell area; the expression of major histocompatibility complexⅡ(MHCⅡ) on DC was up-infected mice. TEM showed that the DCs in RC strain-infected mice spleens were more active than that in N strain-infected mice. Conclusion Infection of RC strain P. berghei increases mature DCs in the spleen, which induces the proliferation of B cells and immune response.

Key words: Plasmodium berghei, Chloroquine resistance, Spleen, B-cell, Dendritic cell, Mouse