After I did Ficoll separation for blood samples of breast cancer patients (collected in EDTA tubes) I kept the above clear plasma layer in falcon tubes at freezer of -20 degree celsius.....I thawed them yesterday to find a viscous white clumps of mucosal consistency...what is that ?????
I think you have to use other anticoagulant and to count the cells and to avoid cell contamination before freezing.
Did you centrifuge the plasma after removing it from the ficoll gradient?
This will get rid of the platelets (which remain in the plasma layer) and any white blood cells aspirated from the ficoll layer.
I think these precipitates or clots are cryoglobulins. In my experience EDTA-plasma often develop such turbidity after freeze-thawing (but not exclusively EDTA also other anti-coagulants or even serum) . Centrifuging even at low speed will remove these. If centrifuging is not allowed, often this clots can be removed mechanical with pipet tips, a small hook or a small sieve (like a tea sieve).
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