Taxotere, a semisynthetic derivative similar to taxol, has shown promi
sing results in vitro and in preliminary in vivo studies. We have prev
iously reported that taxol at 10 mu g/ml suppressed the cytotoxic func
tion and activation of natural killer cells and major histocompatibili
ty nonrestricted (MHC-NR) T cells against the ovarian cell line OV-277
4 and the erythroleukemia cell line K-562. In this paper, we investiga
ted the effect of taxotere on lymphocyte function and found that a sup
pression of MHC-NR cytotoxicity of naive lymphocytes is only seen at h
igher doses of taxotere (50 mu g/ml). At the concentrations of 10 and
50 mu g/ml, taxotere did not have any effect on the cytotoxic function
of IL-2-preactivated lymphocytes. On the contrary, both taxol and tax
otere caused a significant suppression of lymphocyte growth and activa
tion with IL-2 at 10 and 50 mu g/ml. Both drugs (at the concentration
of 10 mu g/ml) were potent inhibitors of the growth of the tumor cell
lines OV-2774 and K-562. In conclusion, despite the fact that taxotere
shares with taxol a potent antitumor effect, it seems to be less supp
ressive for lymphocyte cytotoxicity, an effect clearly desirable in ca
ncer therapy. (C) 1994 Academic Press, Inc.