Table 1

Effect of TMZ on NK activity of three MNC samples endowed with different OGAT activity

Donor1-aOGAT Activity1-bTMZ IC501-c
fmol/mg protein μM
11445  ± 19361  (285–455)
10792  ± 26362  (316–413)
 91400  ± 46408  (309–539)
  • 1-a MNC, obtained from the indicated donors, were exposed to graded concentration of TMZ (62.5–500 μM) for 4 h, washed, and tested for cytotoxic activity against K562 target cells, using a51Cr-release assay (see Materials and Methods).

  • 1-b OGAT activity is expressed in terms of fmol of3H-methyl groups transferred per mg of protein in cell extract. Each value represents the arithmetic mean ± S.E. of at least three independent experiments.

  • 1-c MNC sensitivity to TMZ is expressed in terms of IC50[i.e., the concentration of drug capable of inhibiting MNC cytotoxic activity by 50%, calculated on the regression line in which KC (106) values were plotted against the logarithm of drug concentration]. In parentheses, confidential limits of IC50.