Cutaneous granulomatous response to BCG cell walls with reference to cancer immunotherapy.

A chronic inflammatory response produced by cell walls of Mycobacterium bovis strain BCG associated with microscopic oil droplets (BCG CW-O) was studied with reference to the tumor-regressing ability of this preparation. When BCG CW-O was injected intradermally in the footpads of guinea pigs, intense inflammation developed at the site of injection and in the draining popliteal lymph node. This was characterized histologically as granulomatous inflammation. The intensity of the response was related to the dose of BCG CW-O. Cell walls without oil produced the same type of inflammation but much less in degree. Data are presented that demonstrate the immunological nature of this response and classify it as a cell-mediated immune reaction. Ramifications of this chronic inflammatory reaction occurring at the site of a tumor are discussed.