Immunoglobulin in tophi and on the surface of monosodium urate crystals.

By means of immunohistologic techniques IgG, IgM, and to a lesser degree, IgA were found in the intercrystalline matrix of gouty tophi. Smaller amounts of IgG and IgM were inconstantly found in association with tissue deposits of calcium pyrophosphate. When a technique of immune agglutination was used, the affinity of all three major classes of immunoglobulin to the surface of monosodium urate (MSU) crystals was demonstrated. Immunoglobulin and fibrin were found on MSU aspirated from large tophi.