Related Experiment Videos
Differential function of polymorphonuclear leukocytes between in vivo and in vitro in tumor-bearing mice
N Shinomiya1, S Tsuru, M Tsugita
1Department of Microbiology, National Defense Medical College, Saitama, Japan.
Abstract:
In the present report, we compared activities of polymorphonuclear leukocytes (PMN) such as phagocytosis and bactericidal activity in vivo with those in vitro in sarcoma 180 (S 180)-bearing mice. Mice showed a remarkable leukocytosis and in increase in PMN fraction of peripheral blood leukocytes (PBL) after intraperitoneal injection of S 180 cells. Tumor-bearing mice infected with Escherichia coli (E. coli) intravenously and intraperitoneally showed an apparent delay in the clearance of bacteria compared to the non-tumor-bearing control mice. However, PBL of tumor-bearing mice showed a high phagocytic activity against beads and a high chemiluminescence (CL) activity. Dichlorofluorescein (DCFH) oxidation capacity of peripheral blood PMN in S 180-bearing mice after stimulation with phorbol myristate acetate (PMA) was about the same or a little stronger than that in control mice. On the contrary, serum and ascites of tumor-bearing mice strongly suppressed the phagocytic and bactericidal activities of casein-induced PMN against E. coli. During the early phase of E. coli infection, serum level of complement (C3) was not depressed in tumor-bearing hosts. From these results, it is concluded that leukocytosis and activation of functions of PMN in tumor-bearing mice were observed in vitro but they were not effective for the protection in the early phase of actual E. coli infection in vivo. The delay of in vivo clearance may be accounted for by a suppressive effect of serum components in tumor-bearing mice.
Insights
Tumor-bearing mice showed increased polymorphonuclear leukocytes (PMN) in vitro, but impaired bacterial clearance in vivo. This suggests tumor-derived factors suppress crucial immune cell functions during infection.
Area of Science:
- Immunology
- Cancer Biology
- Microbiology
Background:
- Malignancy can alter host immune responses, impacting susceptibility to infections.
- Polymorphonuclear leukocytes (PMN) are critical for combating bacterial pathogens.
- Sarcoma 180 (S180) is a murine tumor model used to study cancer-host interactions.
Purpose of the Study:
- To compare the in vivo and in vitro activities of PMN in mice bearing S180 tumors.
- To investigate the phagocytic and bactericidal functions of PMN in tumor-bearing mice infected with Escherichia coli (E. coli).
- To determine the role of serum and ascites components in modulating PMN activity.
Main Methods:
- Induction of S180 sarcoma in mice.
- Intravenous and intraperitoneal infection with E. coli.
- Measurement of bacterial clearance, peripheral blood leukocyte counts, and PMN activity (phagocytosis, chemiluminescence, DCFH oxidation).
- Assessment of serum and ascites suppressive effects on PMN functions.
Main Results:
- S180-bearing mice exhibited leukocytosis with an increased PMN fraction.
- In vitro, PMN from tumor-bearing mice showed high phagocytic and chemiluminescence activity.
- In vivo, tumor-bearing mice had delayed bacterial clearance compared to controls.
- Serum and ascites from tumor-bearing mice significantly suppressed PMN phagocytic and bactericidal activities against E. coli.
Conclusions:
- Leukocytosis and enhanced in vitro PMN function in tumor-bearing mice do not translate to effective in vivo protection against E. coli infection.
- Suppression of PMN activity by serum/ascites components likely accounts for the delayed bacterial clearance in tumor-bearing mice.
- Tumor-induced alterations in host immunity can impair the host's ability to clear bacterial infections.