The thermodynamics of both normal and abnormal (disease-associated) protein solubility has been examined. It is shown that the atypical behavior of monoclonal cryoimmunoglobulins can be explained by the formation of one or a few additional electrostatic contacts or, less frequently, a larger number of van der Waals interactions in the protein-rich solid phase relative to normal immunoglobulin. It is hypothesized that cryoimmunoglobulins represent the outer edge of the solubility distribution of total serum immunoglobulin.
