A patient presented with ahritis and purpura. Laboratory examination showed monoclonal and polyclonal cryoglobulins. Histopathology showed deposits of cryoglobulins around the vessels. The patient should be tested for which of the following

HCV Cryolobulin Cryolobulins are abnormal proteins that have unsual propey of precipitating from the serum specimen when it is chilled in the laboratory and redissolving into the serum upon rewarming. The biochemical propeies that promote cqoprecipitation are not well understood but three different types of cryoglobulins have been described. Type I This type of moglobulin contains a monoclonal inununoglobulin (IgM) and is most often due to underlying multiple myeloma or waldenstroms macroglobulinetnia. Type II or Essential ,nixed cryoglobulinemia (contains mixture of two antibodies) This type of cryoblobulin contains both a polytonal IgGdeg (which may either act as on antigen or be directed against an antigen) and a monoclonal(' IgM rheumatoid factor directed against the IgG. Most cases are due to chronic infection with hepatitis C virus('. Type III This also has mixed cryoglobulin but both the IgG and the rheumatoid factor IgM are polyclonalQ. This condition is often seen in chronic inflammatory and autoimmune disorders (such as lupus and leucocytoclastic vasculitis) lymphoproliferative malignancies and in as many as one half of cases HCV infection. Cryoglobulinemia may also be classified based on the association with an underlying disease : -Essential mixed cryoglobulinemia When the cryoglobulins are a mixture of various antibody types and forms for unknown reasons, the condition is called essential mixed cryoglobulinemia. However the discovery of a close association between hepatitis virus (HCV) and mixed cryoglobulinemia has tasted doubt on the existence of essential or idiopathic cryoglobulinemia. Current evidence suggests that in majority of cases essential mixed cryoglohulinemia occurs when an aberrant immune response to Hepatitis C infection leads to formation of immune complexes consisting of :-- Hepatitis C antigen - Polyclonal hepatitis C specific IgG - Monoclonal IgM rheumatoid factor These immune complexes are thought to outstrip reticuloendohelial clearing activity. Tissue damage result from immune complex deposition and complement activation.