Immunospecific eosinophil infiltration of a mouse mammary carcinoma.

In histological examinations of intramammary implants of mammary carcinoma MC2, it was found that eosinophils began appearing at the implants in numbers well above normal after 3 to 4 wk of immunization. Massive invasion of tumor tissue by eosinophils did not become evident until the mice were strongly immunized, after at least 5 wk. Eosinophilia developed after 5 wk of immunization, with blood counts reaching an average high of 530 per mm3 (5.8%) compared to a normal count of 90 to 100 per mm3 (1.1%). By implanting MC2 and a second, immunologically distinct mammary carcinoma into the same mice, it was shown that the attraction of eosinophils to MC2 was immunospecific. By passive transfer of immune plasma, it was shown that the local eosinophil response was promoted by specific immune plasma factors.