Cryoglobulins: detection, quantification, immunochemical characterization and clinical expression

Abstract

Serum cryoglobulins consist of single monoclonal immunoglobulin or immune complexes composed of two or more classes of immunoglobulins that reversibly precipitate from serum on cooling. Cryoglobulins are immunochemically categorized into three types: type I, containing a single monoclonal immunoglobulin; type II, mixed monoclonal/polyclonal immunoglobulins, and type III, composed of polyclonal immunoglobulins.
Our goal was to detect, quantify and immunochemically characterize cryoglobulins in patients with diseases and symptoms associated with cryoglobulinemia, to determine the incidence of diseases and symptoms observed in patients with cryoglobulinemia.
We studied 140 patients, mean age 42 years (range: 16-76), sex ratio Female / Male 110/30. Cryoglobulins were present in 63 out of the 140 patients (45%). The cryocrit range found in all patients was 0.5 to 30%. Of the 63 patients with positive cryoglobulins, three (5%) were type I with a cryocrit range of 0.5 to 30%, six (10%) were type II with a cryocrit range of 0.5 to 16%, and 54 (85%) were type III with a cryocrit range of 0.5 to 16%.
We found high frequency of type III cryoglobulins in concordance with the diseases associated with cryoglobulinemia included in this study. Although we found superposition, the majority of type III cryoglobulins had low cryocrites, while type I and II had high concentration. 
Investigations of cryoglobulins are necessary in autoimmune, lymphoproliferative and chronic infectious diseases, resulting in an important support for diagnosis in patients with symptoms associated with cryoglobulinemia.