Cryoglobulins are immunoglobulins that persist in the serum, precipitate at cold temperature and resolubilize when rewarmed Types Type I is often associated with hematological disorders. Type II and III are mixed cryoglobulins, composed of different immunoglobulins with a monoclonal component in type II and only polyclonal immunoglobulins in type III. Mixed cryoglobulins are associated with connective tissues or infectious diseases Hepatitis C virus is involved in most of "essential" mixed cryoglobulinemia