Immunotherapy of guinea pigs with a transplanted hepatoma: comparison of intralesionally injected emulsions containing heat-killed Nocardia rubra, Mycobacterium bovis (BCG) and Mycobacterium phlei.

Heat-killed cells of Mycobacterium bovis (BCG), Mycobacterium phlei and Nocardia rubra were each tested in emulsified form for their ability to cause regression of established dermal transplants and lymph node metastases of a syngeneic hepatocarcinoma in guinea pigs. On a weight basis, BCG was superior to N. rubra in causing tumor regression. Under the conditions tested N. rubra was inferior to M. phlei in its antitumor activity. M. phlei and BCG were approximately the same in their therapeutic potency. In BCG-sensitized guinea pigs, N. rubra provoked a weaker delayed cutaneous hypersensitivity (DCH) reaction than did BCG. In N. rubra-sensitized guinea pigs, BCG provoked a weaker DCH reaction than did N. rubra. Purified protein derivative of M. tuberculosis was more active in eliciting DCH in BCG-sensitized guinea pigs than in animals sensitized with N. rubra.