Tritiated thymidine incorporation by peripheral human lymphocytes stimulated with phytohemagglutinin (PHA) was investigated in 18 colorectal carcinoma patients (seven with localized tumor and 11 with metastatic tumors). The effect of sera obtained from these patients on lymphocytes from control patients was also studied.
The mean mitotic index of PHA-stimulated versus nonstimulated lymphocytes from all tumor patients was 29.2; from patients with localized tumors, 23.0; from patients with metastatic tumors, 26.0; and from controls, 29.4. In the presence of sera from tumor patients, the mitotic index in all tumor lymphocytes was 47.1; from localized tumor patients, 53.7; from metastatic tumor patients, 43.8; and from control lymphocytes, 47.4.
No substantial difference in mitotic index was detected in normal compared to tumor patient lymphocytes with or without normal or tumor serum.