Response of mammalian cells to bleomycin-induced potentially lethal and sublethal damage.

Both dividing and nondividing cells were able to recover from bleomycin-induced potentially lethal damage, but not from sublethal damage. The recovery from bleomycin-induced potentially lethal damage by nondividing cells was twice as great as that exhibited by dividing cells; and, potentially lethal damage recovery was sufficiently high for cells in both growth states to conceal the true response to sublethal damage. Through the use of integral dose fractions of bleomycin, the recovery from potentially lethal damage can be reduced significantly. These data suggest that closely spaced treatments with fractionated doses of bleomycin may be a more effective means of eradicating tumors containing large nondividing cell populations in vivo.