Effect of group A streptococci on transplantable leukemia of mice.

Bacteria or their products have repeatedly been reported to have a beneficial effect on human neo plastic disease (@l, 7, 192).The earlier work has been reviewed by Shear (8), Shwartzman (9), and Andervont (1). Since then, many additional ob servations on tumor inhibition or regression asso ciated with naturally occurring or artificially in duced infections have been reported (4). Despite the extensive literature concerning the effects of infectious agents on the course of tumors and leukemias, there is little information concerning the mechanism by which microorganisms exert their beneficial effect. It was believed that the superimposition of a localized streptococcal adeni tis upon a localized lymphoma would provide an experimental model to help elucidate the mecha nism by which an infectious agent interferes with tumor growth. The intranasal deposition of ascites-form leu kemic cells (L4946) in AKR mice produces tumor growth initially confined to submaxillary and cervical lymph nodes (3). Similarly, the intranasal deposition of Group A streptococci is also fol lowed by a regional adenitis which remains con fined to the submaxillary and cervical lymph nodes for several days (3) . No foci of tumor or bac terial multiplication occurred between the nasal mucosa and the submaxillary nodes, and thoracic extension with systemic dissemination of the tumor never preceded the local disease. Bactere mia and dissemination of streptococci rarely oc curred before necrosis of submaxillary nodes, sug gesting that the afferent lymphatics from the nasal mucosa were the route by which tumor cells and streptococci reached the submaxillary nodes. This report describes experiments in which mice re ceived tumor cells intranasally and were chal lenged 48 and 792hours later with Group A strep tococci.