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M Beran, BS Andersson, P Kelleher, K Whalen, K McCredie and J Gutterman
In vitro characteristics of response to recombinant tumor necrosis factors
alpha (rTNF-alpha) and beta (rTNF-beta) were studied in six human
myelogenous leukemia cell lines. Heterogeneity of the response to rTNF was
observed, and one line (K562) was resistant. No enhancement of cell growth
was noted in any cell line. The dose-response curves for rTNF-alpha were
characteristically sigmoid, the maximum inhibitory effect occurring between
25 and 200 ng/mL. Nonresponsiveness within this range indicated resistance
that could not be overcome, even with very high doses of rTNF alpha. A
similar response of sensitive and resistant lines occurred after exposure
to rTNF-beta. The clonogenic cells were more sensitive than the overall
population to the action of rTNF alpha, and prolonged exposure was
necessary for manifestation of the effect. Concomitant exposure to
recombinant interferon-alpha (rIFN- alpha) increased the response of two
cell lines to rTNF-alpha, but no clear synergistic action could be
demonstrated. The addition of rIFN- gamma was without effect. Variations in
the rTNF-alpha-induced proliferative response could not be explained by
differences in the number of binding sites per cell or their affinity for
rTNF-alpha. That the clonogenic cells showed a higher sensitivity than the
whole population might indicate a preferential effect on more primitive,
actively proliferating cells with high growth potential.
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| Copyright © 1987 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||