Delayed cutaneous hypersensitivity reactions to membrane extracts of human tumour cells.

Autochthonous tumour cell membrane extracts produced delayed hypersensitivity reactions in patients with a variety of neoplastic diseases. When tested at low protein concentrations (≤0·33 mg/0·1 ml), autochthonous tumour extracts produced positive reactions in 50% of non-anergic cancer patients. The same dose of autochthonous leucocyte membranes produced a significantly lower incidence of positive reactions (10%) in normal volunteers. In contrast, the cancer patients were less reactive than the normal volunteers to a battery of standard skin test antigens. In patients with acute lymphocytic leukaemia, positive reactions were more often obtained during remission. The protein concentration of the extracts was found to be an important factor in these studies. Extracts with high protein concentrations elicited positive reactions in both the patients and in the normal volunteers. It remains to be determined whether the reactions to the high protein concentrations are due to non-specific inflammation or to a low level of autoimmunity in both patients and controls.