ABSTRACT
Objective To understand the differences between infiltration of mononuclear-macro-phages and neutrophils during Leptospira interrogans (L.interrogans) infection and the underlying mecha-nisms. Methods Histological changes in mouse lung, liver and kidney tissues were detected using hema-toxylin and eosin (HE) staining following infection of C3H/HeJ mice with L.interrogans serovar Lai strain 56601. Infiltration of peripheral blood-derived CD11b+mononuclear-macrophages and Ly6G+neutrophils in lung,liver and kidney tissues collected form L.interrogans-infected C3H/HeJ mice was detected with immu-nohistochemistry. Levels of mononuclear-macrophage chemokines and neutrophil chemokines in serum sam-ples of L.interrogans-infected mice were detected with chemokine detection microarray. Results Lung,liv-er and kidney tissue samples collected from L. interrogans-infected C3H/HeJ mice presented typical his-topathological changes of leptospirosis, such as inflammatory cell infiltration in these tissues, pulmonary hemorrhage,extensive hepatocyte necrosis and serious nephrohemia. Results of immunohistochemical stai-ning showed that a large number of peripheral blood-derived CD11b+mononuclear-macrophages were presen-ted in lung,liver and kidney tissues of L.interrogans-infected mice, but few neutrophils could be found in these tissues. The mouse chemokine detection microarray confirmed that the levels of mononuclear-macro-phage chemokines (I-309,MCP-1,MCP-5,MIP-1α and RANTES) in serum samples of L.interrogans-in-fected C3H/HeJ mice were significantly increased during infection (P<0.05), but the neutrophil chemokines(KC,LIX and MIP-2) analyzed in this study were not notably increased (P>0.05). Conclu-sion Mononuclear-macrophages rather than neutrophils are the major infiltrating phagocytes during L.inter-rogans infection and play a crucial role in the elimination of Leptospira invasion.