cytokine ELISAs-freezing plates? - (Mar/29/2005 )
I am planning to set up a mouse mixed lymphocyte reaction, and am planning to look at the supernatant for IFN gamma release by cytokine ELISA. I am planning to look at a few day time points. Does anyone know if I can either freeze the plates ot put them at 4 degrees before I analyze the supernatants by ELISA?
in my experience, there are basically two types of ELISAs. the one type can not be disturbed by 'bout anything (freezing, blocking at 4°C for 72h, drying up, etc.), and the other ones are more, well let's say "tricky". we use cytokine ELISAs around here very much, and one example for a "stable" ELISA is the human IL-8 ELISA, one example for a tricky ELISA is, yes, you'd expected as much...mouse IFNg! In our hands this ELISA shows strong reactions (i.e. fluctuations in total OD for the same standard concentrations) to minute changes in the protocol like when the coationg occurs in pH 9.3 instead od pH 9.5, or over the weekend, or if it's blocked too long, or, or, or....
So, i'd recommend you to freeze all your samples, collect them till you have all of them ready, and then prepare your ELISA-plate fresly when needed. for freezing and thawing i'd recommend you to make at least two better are more aliquots of each sample, so theat you can thaw one, measure it, dispose it and if needed thaw the other and measure that again. that way you always will measure the same sample, teated exacly the same (i.e. once frozen, once thawed...). repeated freeze/thaw cycles are not becoming for cytokines in general....