Abstract

Lymphocyte responses to stimulation with phytohaemagglutinin (PHA) have been compared in 20 patients with large intestinal cancer, 10 patients whose large intestinal cancers have been removed, and in 30 age- and sex-matched control individuals. Responses were markedly reduced in the tumour-bearing patients and were unaffected by substituting normal for autologous plasma during incubation. Responses, however, were normal after tumour resection suggesting that the defect in lymphocyte responsiveness is a reversible one and related to the presence of tumour tissue.