Protéines cryoprécipitantes en pathologie : cryoglobuline et cryofibrinogène

Cold is responsible for clinical symptoms in some subjects, caused by seric or plasmatic proteins precipitation in small or medium vessels, as cryoglobulins or cryofibrinogen. Cryoglobulins are constituted with monoclonal or polyclonal immunoglobulins, with sometimes rheumatoid factor activity. They are essential or secondary in immunoproliferative, autoimmune or infectious diseases. Cutaneous vasculitis (purpura, Raynaud phenomenon), arthralgies, peripheral neuropathies or renal failure are the main cryoglobulinemic symptoms. Cryofibrinogen, associated with fibronectin and others plasmatic proteins, is involved in cold triggered thrombotic events (purpura, livedo, ulceration, necrosis). Strict pre-analytic conditions are essential to evidence cryoproteins in serum or plasma : blood sample, transport and coagulation at 37 °C. Cryoprotein analysis must be initiated in evocating clinical context, because of difficulties in cryoglobulinemia or cryofibrinogenemia diagnosis : first, these cryoproteins could be present in asymptomatic subjects, second, cryoprotein concentration is not proportional to symptom severity. Nevertheless, biologic study is essential, even in low concentration, because of potential renal or neoplasic complications of these cryoproteins.