TABLE 2.
Correlation between the levels of PI-9 in transfected FDC-P1 clones and their resistance to granzyme B-or perforin-mediated apoptosis
| Clone | Level of PI-9 expression (arbitrary units)a | % Inhibition of apoptosisb |
|---|---|---|
| FDC-neo | 0 | 0 |
| FDC-PI9/8 | 9.6 | 17.0 |
| FDC-PI9/6a | 38.4 | 43.6 |
| FDC-PI9/11 | 51.6 | 58.3 |
| FDC-PI9/6b | 71.6 | 62.2 |
Levels of PI-9 in the clones were compared by FACS analysis and are expressed in arbitrary units (see Materials and Methods). The vector-transfected cells (FDC-neo) do not express PI-9, as assessed by immunoblotting and RNA analysis. Expression of PI-9 by the transfected clones was confirmed by immunoblotting (data not shown).
Values represent the percent reduction in TUNEL-positive PI-9-expressing cells compared to FDC-neo cells following exposure to purified granzyme B and perforin (as measured by FACS). The results are representative of three experiments in which cells were analyzed by TUNEL and FACS for apoptosis. Under these conditions, 40% of the cells in the FDC-neo control samples routinely became apoptotic.