Acute inflammatory changes in subcutaneous microtumors in the ears of mice induced by intravenous CM101 (GBS toxin).

CM101, a bacterial polysaccharide derived from group B streptococcus, induces pronounced inflammatory changes in and around tumor blood vessels 60 min after i.v. injection. A technique has been developed for implanting small numbers of tumor cells in the ear skin of mice. This allows macroscopic examination of the tumor and its supporting blood vessels as it reaches the 10000 cell size and greater. Treatments can be monitored in this model for effects on small "metastatic-like" tumor nodules by direct observation and by histological examination. Inflammatory changes were indicated by increased numbers of polymorphonuclear leukocytes (PMN) adjacent to and marginating within thin-walled blood vessels and within the tumor tissue. PMN were seen in the process of migrating through venules and enlarged capillaries, each with prominent endothelial cells. Tumor morphology was variable with evidence of occasional single necrotic cells. This contrasted with tumors in ears of dextran-treated or untreated mice, which had uniform tumor morphology, and acute inflammatory cells were rarely present.