Cyclophosphamide‐Induced Bacterial Translocation in Escherichia coli C25‐Monoassociated Specific Pathogen‐Free Mice

Abstract The kinetics of bacterial translocation (BTL) from the intestine to the mesenteric lymph nodes (MLN) and the number of peripheral white blood cells (WBC), macrophages in Peyer's patches (PP) and M‐cells on the surface of cecal PP after cyclophosphamide (CY) injection were examined in penicillin‐G and streptomycin sulfate decontaminated and Escherichia coli C25‐monoassociated specific pathogen‐free mice. WBC were counted to confirm the immunological state of the mice. Until 8 days after CY injection, the number of WBC, bacteria in MLN and macrophages in PP decreased, but then significantly increased on day 14. The levels again decreased to the control levels on day 16. Although the number of M‐cells decreased up to day 8, it did not return to the control level on day 16. These results indicate that BTL is stimulated in an immunopotentiated state after CY injection, and this phenomenon may be closely related to the number of macrophages in the blood and PP.