Changes in serum cytokine levels during induced whole body hyperthermia

Background

Recent data from our laboratory demonstrated a significant decrease in the number of circulating T helper cells and monocytes as well as in the expression of IL-2. receptors on T cells during induced whole body hyperthermia [1,2]. The aim of further investigations was to analyze the influence of these effects on the function of TH1 cells, TH2 cells and monocytes. Therefore, we measured the levels of IL-2, IL-4, IL-6 and IFN-? in the blood of cancer-patients, undergoing whole body hyperthermia of 42°C. This is used as part of so called `systemische Krebs-Mehrschritt-Therapie' (sKMT) in our clinic.

Methods

Cytokine levels of 9 patients were measured by an ELISA technique. Blood samples were obtained before beginning of therapy at 37°C, at 40°C, at the end of the plateau of 42°C, at 37°C again, as well as after 20 h (on the next morning). Time between the first four investigations was about 2 h. Cytokine levels were compared by using a Wilcoxon rank sum test.

Results

We found a reversible, significant decrease (P = 0.017) of IL-2 at 42°C (Fig. 1), whereas the levels of IL-4 and IFN-? decreased slightly (data not shown). In contrast, IL-6 showed a sustained increase (P = 0.008) during and after therapy which returned to baseline after 20 h (Fig. 2).

Conclusion

Despite a similar decrease in the number of both circulating T helper cells and monocytes, there seems to be a different change in the function of these cells during whole body hyperthermia up to 42°C. IL-2, which is postulated to be mainly produced in TH1 cells, decreased significantly; IL-4 and IFN-?, mainly produced in TH2 cells, decreased slightly and IL-6, one of the main products of monocytes, showed a significant increase. Further investigations are necessary to verify these results.

Figure 1-2.

IL-2 (Fig. 1) and IL-6 levels (Fig. 2) during induced whole body hyperthermia. Data are presented as mean-values with SEM.