Mixture of polyclonal IgM and IgG.- Exists rheumatoid factor (IgM) activity• Type II and III- Occurs in patients with rheumatic diseases, Sjogren's syndrome, and chronic infections.- Frequently presents as vasculitis, most commonly with recurrent lower extremity purpura, glomerulonephritis, and peripheral neuropathy.- Presents the circulating cryoprecipitate immune complexes in the patient’s serum.