Immunological alterations induced by adjuvant treatment of postoperative colon carcinoma Duke's B or C with levamisole in combination with 5-FU.

Background: Postoperative 5-FU combined with levamisole increases 5 year survival in colon cancer patients (Duke C) by 30% (1). In order to investigate the potential immunological mechanism, we determined lymphocyte subtypes and markers of immune activation in 22 patients before and during one year of postoperative adjuvant treatment.

Methods: Before and regularly during treatment, according to the scheme described by Moertel (1), major lymphocyte subsets were quantified by flow cytometry. Serum neopterin, soluble IL2-receptors, beta 2-microglobulin, TNF-alpha and interferon-gamma were determined by Elisa.

Results: The CD4/CD8 ratio increased significantly after levamisole was added to the treatment, as did the levels of soluble IL2-receptors. The percentages of T-cells expressing the interleukin 2 receptor followed a similar trend. The levels of neopterin tended to decrease during the combined treatment course. This was paralleled by a progressive fall in the proportion of T-cells expressing HLA-DR.

Conclusions: The treatment induced significant and consistent alterations in major immunological mediators and lymphocyte subtypes. It remains to be established whether these changes are related to the therapeutic effect.