ACUTE INFLAMMATORY CHANGES IN SUBCUTANEOUS MICROTUMORS IN THE EARS OFMICE INDUCED BY INTRAVENOUS CM101 (GBS TOXIN)

CM101, a bacterial polysaccharide derived from group B streptococcus, induces pronounced inflammatory changes in and around tumor blood vess els 60 min after i.v. injection. A technique has been developed for im planting small numbers of tumor cells in the ear skin of mice. This al lows macroscopic examination of the tumor and its supporting blood ves sels 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. Inflam matory changes were indicated by increased numbers of polymorphonuclea r leukocytes (PMN) adjacent to and marginating within thin-walled bloo d vessels and within the tumor tissue. PMN were seen in the process of migrating through capillaries, each with prominent endothelial cells. Tumor morphology was variable with evidence of occasional single necr otic cells. This contrasted with tumors in ears of dextran-treated or untreated mice, which had uniform tumor morphology, and acute inflamma tory cells were rarely present.