Deficient mitogen-induced virus plaque-forming cells in patients with localized cancer

The virus plaque assay (VPA), an assay capable of enumerating mitogen- or antigen-sensitive T-lymphocytes in a given cell population, was applied to the study of mitogen responses of peripheral blood leukocytes (PBL) in 50 patients with localized, solid cancers and in 29 normal controls. Concanavalin A (Con A)-responsive virus plaque-forming cells (V-PFC) were significantly reduced in the patients as compared with those of the controls. PBL from 20 of the patients but only 2 of the controls failed to show significant increments in V-PFC over background when cultured in the presence of Con A. This deficient response was also present in the patients when phytohemagglutinin was used as the mitogenic agent. Mitogen-stimulated uptake of [3H]thymidine (TdR) in parallel cultures failed to show a statistically significant difference between the patients and the controls, though some patients showed diminished stimulation in this assay. The VPA thus appeared to detect a defect of T-lymphocyte function not found in the [3H]TdR incorporation assay.