Frank
In cells I have looked at, the response to chemokines is pretty fast, peaks
at about 9 seconds and is pretty much back at baseline after a minute, so
you may miss the peak of the response. I also noticed that the carry over
effect from samples had a great effect, the residual chemokine in the
sample line stimulating the cells before addition of agonist. This of
course is even more pronounced with ionomycin. Flushing the sample line
with PBS for chemokines and ethanol for ionomycin for a few minutes usually
does the trick. Using an ordinary FITC filter (530/30) is better than the
485. How high are your PMT voltages?
Happy fluxing!
Simon