Effects of tumour necrosis factor α and melphalan on the cytokine production of circulating T cells in patients with cancer

Background. The objective of the present study was to investigate the effects of isolated limb perfusion (ILP) with tumour necrosis factor or (TNF-α) and melphalan on circulating T cells from cancer patients using two different methods. Design. Eight patients undergoing an ILP entered the study. At first, the number of T cells at several time points was determined using FACScan. Subsequently, production of interferon gamma (IFN-γ) (T-helper 1) and interleukin (IL) 4 (T-helper 2) was measured at the intracytoplasmic level after stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. IFN-γ, IL-4 and IL-2 (also T-helper 1) production in the whole-blood cell culture system was then determined after stimulation with a combination of anti-CD3/anti-CD28 monoclonal antibodies. Results. An enormous decrease in the number of circulating T cells was observed. In the remaining T-cell population cytokine production (IL2, IL-4, IFN-γ) was depressed, showing the same pattern in both methods. No difference could be detected between the effect of TNF-α and melphalan on Th1 cells and Th2 cells. Conclusions. The results demonstrate that TNF-α and melphalan reduce the number of circulating T cells and at the single-cell level decrease cytokine production in the remaining circulating T cells. No selective effect of TNF-α on Th1 or Th2 cells could be detected. If the impaired T-cell function is representative of all T cells remaining in the systemic circulation, this could help to explain the tolerability of high TNF concentrations after ILP, perhaps by decreasing the synthesis and production of T-cell-derived cytokines.