Lymphocyte fluorescence polarization changes after phytohemagglutinin stimulation in the diagnosis of colorectal carcinoma.

A lymphocyte fluorescence polarization test that measures reactivity to phytohemagglutinin (PHA) has permitted discrimination of a majority of patients with colorectal carcinoma from noncancer individuals. The test involves separation of two lymphocyte fractions from 20 ml venous blood on a modified leukocyte separation gradient, incubation with PHA for 45 minutes, addition of fluorescein diacetate, and analysis of change in fluorescence polarization. Of 19 colorectal patients tested preoperatively, 13 had a positive stimulation index, 3 a zero index, and 3 a negative index. Of 7 patients with other malignant neoplasms, a positive value was obtained in 6 and a negative value in 1. Of 14 patients with other diseases, a negative value was obtained in 9, zero in 3, and positive in 2. Of 31 normal donors a negative value was obtained in 27, zero in 2, and weak positive in 2. This rapid test promises to develop into a useful cancer-diagnostic method, and elucidation of its biological basis should identify a new cancer marker.