Cryoglobulins; Paraproteins; Pyroglobulins; Antigen-Antibody Complex/immunology; Arthritis, Rheumatoid/blood; Arthritis, Rheumatoid/physiopathology; Cryoglobulinemia/blood; Cryoglobulinemia/etiology; Cryoglobulins/immunology; Cryoglobulins/isolation & purification; Cryoglobulins/metabolism; Humans; Hydrogen-Ion Concentration; Immunoglobulin G/analysis; Immunoglobulin M/analysis; Lymphoproliferative Disorders/blood; Paraproteins/classification; Paraproteins/immunology; Paraproteins/metabolism; Protein Conformation; Purpura/blood; Purpura/physiopathology; Pyroglobulins/classification; Pyroglobulins/immunology; Pyroglobulins/metabolism; Temperature; Vasculitis/blood; Vasculitis/physiopathology; Waldenstrom Macroglobulinemia/blood