Intracerebral delayed hypersensitivity reactions in glioblastoma multiforme patients.

Patients with malignant gliomas who had undergone BCG inoculation were injected intratumorally with PPD to induce an intratumoral delayed hypersensitivity reaction. Histopathological examination of the tumor before and after PPD injections revealed that chronic inflammatory responses were increased after injection in four of the five patients. In no case, however, was the response more than moderate, and in no case did the inflammatory response encompass the tumor at its peripheral margins. Intracerebral delayed hypersensitivity reactions were evoked in humans with acceptable morbidity. The mild reactions evoked did not cause detectable tumor regression.