Role of Lymphatic Drainage on the Development of Calmette-Guérin Bacillus-Induced Granulomas in the Hamster

Abstract

The influence of lymphatic drainage on Calmette-Guérin bacillus (BCG)-induced granulomas was investigated by comparing the time course of granuloma formation in two sites: the hamster footpad and the check pouch, an area deprived of lymphatic vessels. Typical epithelioid granulomas developed in both sites. Whereas in the footpad the size of granulomas increased and the volume of the lesion persisted, in the pouch the lesion decreased in volume. The inoculation of BCG into the footpad of animal with granulomas in the pouch, reactivated the pouch lesions. T lymphocytes were detected by an immunocytochemical technique at the edge of these lesions. Inoculation of the bacteria into the pouch induces suppressive mechanisms which hold down the volume of the lesions induced in the footpad. The cutaneous purified protein derivative (PPD) test, positive in animals inoculated in the footpad, was always negative in animals with granulomas in the pouch. The number of bacteria per microscopic field in pouch granulomas increased from 10 to 1,000 after PPD injection. Evidence that PPD has a direct effect on pouch granuloma cells is given.