why my IFN gamma treated cells still high in TER? - (Mar/25/2006 )

According to my knowledge, IFN gamma would disrupt tight junction and cause disease. So I cultured T84 mololayer cells on transwells and treated with IFN gamma (100ng/ml) after cells are confluence at day 12. The criteria of confluence is the transepithelial resistance (TER) reached stable around 12-13.

But, 24 hours continous exposure to IFN didn't result in tight juction disruption. The TER remains as high as 10. I would expect the TER dropping to at leat 5 if the tight juction is no longer contact.

(I used Corning transwells 3470 which has a 0.33cm2 area and I seeded cells at a density of 1*10^6 cells/cm2; IFN gamma is from sigma and is quite new, aliquoted at 17/11/05)


Can anybody see anything problem with my experiments? Is there any problem in cells or medium or contamination may affect IFN gamma effect? I have no idea what's going on. Any comments please???


Many thanks

from my experience it is difficult to see changes in low teer values.
if you can try another cell line