Comparison of the effects of various clinically applied mistletoe preparations on peripheral blood leukocytes.

The aim of the present study was to compare the biological effects of 12 different clinically applied mistletoe preparations (I, II, III and IV) from the host trees "pinus" (P), "malus" (M), "abies" (A) and "quercus" (Q) on human leukocytes. When the preparations I-P, II-P, III-P and IV-A were added to the whole blood cell cultures of 37 cancer patients (breast cancer, n = 22, colorectal cancer, n = 15) and 34 healthy controls, a significant induction of the cytokines IL-1-beta, IL-2, IL-6, IL-10 and TNF-alpha was found with preparation I-P. A significant induction of IL-1-beta and TNF-alpha was obtained with the preparations II-P and III-P as compared to the nonstimulated control cultures. Induction of IFN-gamma was not found with any preparation. Cytokine induction was comparable in the blood cell cultures of the tumor patients and the healthy controls. When the clinical preparations I-P, I-M, I-Q, II-P, II-M, II-A, III-P, III-M, III-A and IV-P, IV-M, IV-A were tested in cultures of peripheral blood mononuclear cells from 5 healthy donors, differences in the induction of cytokine production and apoptosis were seen after addition of the mistletoe preparations from different host trees. Increased levels of IL-1-beta were found after addition of the preparations I-P and I-M, increased levels of TNF-alpha were measured after addition of preparations I-P and III-A. Induction of apoptosis was most evident with the preparations I-M, I-Q, III-M and IV-A. Neither cytokine induction nor apoptosis could be correlated to the amount of lectins found in the preparations. Stimulation of separated CD4(+)-, CD8(+)- and CD14(+)-cells from 5 healthy donors with the above noted preparations revealed an induction of IL-1-beta and TNF-alpha production by the preparations I-P, I-M and I-Q mainly in monocytes and to a minimal extent in lymphocytes. Also apoptosis was seen mainly in CD14(+)-monocytes. From these results it is concluded that both, apoptosis and cytokine production are induced differentially in leukocyte cultures by clinically applied mistletoe preparations. However, there is no correlation between the biological effects and the lectin content of the various preparations and none of them were comparable with respect to the extent of these effects. Therefore, it may be expected that clinical studies with different preparations are not comparable either.