Abstract
The level of peripheral blood platelets was determined after i.v. injection of Corynebacterium parvum in normal C57BL mice and in those bearing the Lewis lung carcinoma. Twenty minutes after injection of a formalin-killed active strain (CN6134, (CN6134, which inhibited tumour metastases) or a killed inactive strain (CN 5888, which did not inhibit metastases) the number of circulating blood platelets was reduced by 50%. The level of platelets returned to control values by 8 h after the active, and by approximately 3 days after the inactive strain. The active strain alone caused a second and prolonged fall in platelet numbers, from approximately 16 h to 21 days after injection. Heparin given 3 X weekly to these mice restored the platelet count to normal values by 10 days after injection of active-strain C. parvum. The level of platelets in tumour-bearing mice was essentially similar to that in normal mice. Possible causes of the thrombocytopenia and the significance of platelets in metastasis are discussed.
Highlights
Twenty minutes after injection of a formalin-killed active strain (CN 6134, which inhibited tumour metastases) or a killed inactive strain (CN 5888, which did not inhibit metastases) the number of circulating blood platelets was reduced by 50.0o The level of platelets returned to control values by 8 h after the active, and by 3 days after the inactive strain
The protection afforded by this vaccine has generally been attributed to its stimulatory effect on the reticulo-endothelial system (Halpern et al, 1966: Scott, 1974). We reported another effect of C. parrurn which may influence metastasis (Lampert et al, 1977): a prolonged intravascular coagulation reaction occurs after i.v
Fibrin thrombi were present in the lungs (Lampert et al, 1977) and the level of circulating blood platelets was reduced
Summary
Heparin given 3 x weekly to these mice restored the platelet count to normal values by 10 days after injection of active-strain C. parvum. IN THIS investigation, 2 strains of formalin-killed C. parvum were used: an active strain (CN 6134) which causes hepatosplenomegaly and inhibits tumour growth, and an inactive one (CN 5888) which does not have these effects (Adlam and Scott, 1973; Bomford and Olivotto, 1975). The protection afforded by this vaccine has generally been attributed to its stimulatory effect on the reticulo-endothelial system (Halpern et al, 1966: Scott, 1974) We reported another effect of C. parrurn which may influence metastasis (Lampert et al, 1977): a prolonged intravascular coagulation reaction occurs after i.v. C. parvum, resulting in thrombi in hepatic, splenic and pulmonary vessels. We wish to report the effects of systemic C. parvrum on platelet levels in normal and tumour-bearing mice
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