Phenomenological analysis of the dynamics of cryoaggregation by light-scattering spectrometry.

Cryoglobulins are proteins that precipitate at temperatures below 37 degreesC. Coldinduced precipitation of proteins may occur in vivo secondary to several important diseases, and lead to pathological manifestations involving different organs. Cryoprecipitation may be observed in vitro by exposing serum samples, supposed to contain cryoglobulins, to low temperatures, but this needs several days to occur. Proteinprotein interactions leading to cryoprecipitation are still poorly understood and the knowledge of the underlying mechanism may be relevant to the understanding of the onset of pathological manifestations. Using lightscattering spectrometry, we studied cryoprecipitation occurring in vitro at different temperatures and cryoglobulin concentrations. We describe the kinetics of the coldinduced precipitation of mixed cryoglobulins, measured as increase in turbidity. The plots obtained demonstrate that the cryoprecipitation did not occur as a singlestep reaction, but consisted of four distinct phases where both temperature and cryoglobulin concentration affected the immune complexes formation. Light scatter spectrometry may provide a simple, sensitive and rapid method for the detection of cryoglobulin