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The only thing that I can propose is that the paraprotein is forming immune complexes. Red cells have a high capacity to bind these. In this case they are binding the small complexes and preventing larger insoluble complexes forming. Once the red cells are removed the complexes continue to form but can form larger and larger complexes until they precipitate. Therefore this is not a true "cryoglobulin". The reason that a precipitate forms above the gel could be that this acts as a physical barrier preventing access of the complexes to the red cells, so again they can increase in size until they precipitate. Pamela Riches On Wed, 23 Jun 1999 12:25:54 +1000 Geoff Whittaker <[log in to unmask]> wrote: > Dear Mailbase Members, > > I received an interesting sample in the laboratory with > some unusual properties that maybe some one could shed some > light on. There were two blood samples collected from the > one patient, a serum sample in a gel separated tube and an > EDTA plasma sample. The patient was found to have the > following results: > > Total protein = 128g/L > Albumin = 18g/L > IgG = 89g/L > Kappa = 98g/L > IgG kappa paraprotein by immunofixation. > > When the serum sample is separated it forms a gelatinous > mass with the appearance of denatured serum within 30 > minutes (cryoglobulin/cryopreciptitate). Separating the > serum and immediately putting it into a 37 C water bath > maintains the sample in a liquid state with normal > appearance. When the primary sample tube was retrieved from > the 4 C cold room after being there for 3 days, the serum > above the gel separator had formed a gelatinous mass, > however, the serum below the gel separator which was in > contact with the red cell clot had normal appearance. This > could be seen quite easily through the plastic primary tube > as the clot had retracted further on standing. The EDTA > plasma sample was recovered after 3 days storage at 4 C and > the plasma appeared quite normal as the red cells had > settled to the bottom. Separating the plasma from the red > cells caused it also to form a gelatinous mass. Trying to > warm the serum or plasma sample at 37 C overnight does not > cause the sample to re-"liquify", i.e. once the > conformation of the protein has changed, cannot revert it > back to a liquid state. > > In summary, the serum and EDTA plasma when in contact with > the red cells have a normal appearance, even when > refrigerated. When the serum or plasma is separated from > the red cells, it denatures irreversibly. Separating > the sample and putting it immediately into a 37 C bath, > maintains the sample in a liquid state for a limited time. > > Why is it that the serum or plasma does not denature when > in contact with the red cells even at 4 C for a number of > days, but when removed it denatures?? > > Thanking you in advance for any replies posted. > > Geoff Whittaker > Hospital Scientist Clinical Chemistry > South Western Area Pathology Service Liverpool Hospital > Sydney. Email: [log in to unmask] > <mailto:[log in to unmask]> ----------------------------------- pamela riches [log in to unmask] St. Georges Hospital Medical School Opinions expressed those of the author and not the institution %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%