Properties of cryofibrinogen

Cryofibrinogen is an abnormal protein that precipitates when plasma is stored at 4°C and redissolves at 37°C. It is only present in plasma, not serum. These samples were from a 78 year old patient with cryofibrinogen-associated glomerulonephritis.

(A) Samples of the patient's serum and plasma at 4°C. The arrow shows the precipitated cryofibrinogen in the plasma sample. Ultrastructural examination of the precipitate revealed similar structures to that seen on his kidney biopsy.