Increased growth rate of a benzo(a)pyrene-induced transplantable tumor in bursectomized chickens

A benzo(a)pyrene-induced transplantable tumor was used to study the effects of bursectomy and thymectomy on tumor development in recipients that were isogenic with the donor for the major histocompatibility locus. Surgical bursectomies and thymectomies were done in different groups of chickens on the day of hatching, with no adjunct treatment. The following day, the experimental and control animals were given 10(3) live tumor cells s.c. Tumor frequency and size were followed weekly. With the experimental protocol used, thymectomy did not significantly affect tumor frequency or growth. Bursectomy did not affect tumor frequency, but the transplanted tumors grew significantly more rapidly in bursectomized than in control animals. Thus, bursectomy and, consequently, the antibody-forming system influence not only virus-induced tumors, but also the development of a chemical carcinogen-induced transplantable tumor line. The data underscore the host-protective role of the antibody-forming system in oncogenesis.