[The significance and function of IFN-gamma on the changes of peripheral blood platelet count during tumor-rejection induced by a low dose of melphalan in C57BL/6 mice].
OBJECTIVE
To investigate the significance and function of IFN-gamma on the changes of peripheral blood platelet count during tumor-rejection induced by a low dose of melphalan in C57BL/6 mice.


METHODS
Mouse tumor rejection model induced by a single dose of melphalan was used in this experiment. Different gene-type tumor-bearing mice (IFN-gamma(+/-) and IFN-gamma(-/-)), which had the same genetic background of C57BL/6, were treated intraperitoneally with melphalan (7.5 mg/kg). Tumor size was observed and recorded every one to three days in these different gene-type mice subsequently. Blood samples were obtained from orbital venous sinus on different days before and after melphalan treatment, and then complete blood counts were performed. The function of IFN-gamma on the efficacy of chemotherapy and the changes of blood platelet count in IFN-gamma(+/-) and IFN-gamma(-/-) mice after melphalan treatment was analyzed.


RESULTS
There was no significant difference in tumor sizes and blood platelet count between IFN-gamma(-/-) and IFN-gamma(+/-) mice (P>0.05). On the first day after melphalan (7.5 mg/kg) treatment, there were no significant changes in tumor sizes between mice in these two groups (P>0.05). Tumors shrank a little in IFN-gamma(-/-) mice and then grew gradually. Tumors relapsed in 2 w after melphalan injection in all IFN-gamma(-/-) mice, while tumor volumes decreased progressively and tumor cured at last in IFN-gamma(+/-) mice. The number of blood PLT in IFN-gamma(+/-) mice increased to (1935+/-378) x 10(9)/L 6 h after melphalan treatment, significantly higher than before (P<0.01); While in IFN-gamma(-/-) mice it was (1183+/-186) x 10(9)/L 6 h after melphalan treatment, no obvious increase than before. There was significant difference in blood PLT 6 h after melphalan treatment between IFN-gamma(+/-) and IFN-gamma(-/-) mice (P<0.01). Later, the numbers of blood PLT in IFN-gamma(+/-) mice decreased gradually and it dropped to normal (1158+/-270) x 10(9)/L on 11th day after melphalan treatment (P>0.05); While it sustained in normal range in IFN-gamma(-/-) mice. There was no significant difference in blood platelet count between IFN-gamma(-/-) and IFN-gamma(+/-) mice.


CONCLUSIONS
Peripheral blood platelet count increased on the first day after melphalan treatment and tumors cured in IFN-gamma(+/-) mice; While tumors relapsed and there is no increase in blood platelet count on the first day after melphalan treatment in IFN-gamma(-/-) mice. These data indicated that the increase of blood PLT count was related to the function of IFN-gamma in tumor-bearing mice in vivo during tumor rejection induced by a low dose of melphalan.
Li
Chuan-gang
CG
The Second Affiliated Hospital of Dalian Medical University, Pathophysiology Department of Dalian Medical University, Dalian 116044, China.
Shu
Xiao-hong
XH
Han
Dan
D
Li
Mo-lin
ML
Notter
Michael
M
Qin
Zhi-hai
ZH
D000818:Animals; D004305:Dose-Response Relationship, Drug; D007371:Interferon-gamma / Q000172:deficiency / Q000378:metabolism*; D008558:Melphalan / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D010976:Platelet Count; D047368:Tumor Burden / Q000187:drug effects
D007371:Interferon-gamma; D008558:Melphalan