Cryoproteins.

Proteins producing phenomena after exposure to the cold are reviewed but concentrating mainly on those that can produce aggregates within the laboratory. From three large series the frequencies were I. Mixed Cryoglobulins (polyclonal 50 p. 100, monoclonal 18 p. 100); II. Monoclonal Cryoglobulin (25 p. 100); III. Cryofibrinogen (3 p. 100) and IV. Cold Agglutinins (polyclonal 2 p. 100, monoclonal 2 p. 100). Mixed cryoglobulins present with any of the features of immune complex disease, but with the onset of renal involvement, over 50 p. 100 of the patients are dead within 5 years. Monoclonal cryoglobulins present with flat lesions in dependent areas, most reflecting an underlying or impending malignant B-cell neoplasm. Cryofibrinogen, missed in heparinised samples, is associated with thrombophlebitis migrans and sometimes underlying cancer, especially of the pancreas. Cold agglutinins cause Raynaud's phenomenon and haemolytic anaemia and the blood must be centrifuged at 37 degrees C. Treatments are discussed and are certainly encouraging in about one-third of the patients.