IMMUNOHISTOCHEMICAL INVESTIGATION OF THYMIDYLATE SYNTHASE IN CERVICAL-CANCER

We prepared a polyclonal antibody against recombinant human thymidylat e synthase (TS) to evaluate its use in immunohistochemical analysis. F ormalin-fixed, paraffin-embedded sections of specimens of cervical tis sue were prepared from 35 patients with cervical cancer. The TS immuno reactivity was studied by employing the peroxidase-labeled antibody me thod with our prepared antibody, At the same time, the TS activity was determined with the 5-fluoro-2'-deoxyuridylate (FdUMP)-TS-binding ass ay in fresh-frozen specimens of these cervical cancers. We observed a positive correlation (r = 0.658) between the degree of TS immunoreacti vity and the TS activity in the binding assay of 9 patients with grade 4 (strongly positive) TS immunoreactivity, while 7 patients (78%) exh ibited a TS activity of 5 pmol/g tissue or greater. Nine patients with a TS immunoreactivity of grade 1 (negative to weakly positive) showed a TS activity <5 pmol/g tissue. The difference between the two groups was statistically significant (p < 0.01). TS expression was easily de tected by the immunohistochemical technique which will allow the asses sment of the relationship between TS activity and patient outcome.