Effect of oxygen radical scavengers on K-cell cytolysis.

We have shown that the hydroxyl radical scavengers sodium benzoate, phenol, dimethyl sulfoxide, sodium formate, and mannitol protect chicken erythrocyte (Ec) target cells from lysis by K-cells in plaque assays. The protection afforded by benzoate, phenol, mannitol, and dimethyl sulfoxide was abrogated if the target cells were pretreated with sodium chromate. Neither superoxide dismutase nor catalase protected Ec target cells, indicating that superoxide and H2O2 are not involved in lysis. The lysis obtained on chromium-treated Ec target cells in the presence of benzoate, phenol, and mannitol is likely due to singlet oxygen, because 1,4-diazabicyclo[2.2.2]octane and bilirubin, singlet oxygen scavengers, protected chromium-treated Ec target cells in the presence of phenol. Ec target cells not treated with chromium were not protected by either of the singlet oxygen scavengers.