Cryoglobulinaemia in tropical splenomegaly syndrome.

Tropical splenomegaly syndrome is an idiopathic disorder consisting of splenic enlargement, hypersplenism, elevated serum IgM levels, and infiltration of lymphocytes in the hepatic sinusoids with Kupffer cell hyperplasia. The syndrome is most commonly encountered in immigrant and indigenous adults residing in malarious areas of the tropics. The present study investigates the role of cryoglobulinaemia in the pathogenesis of this disorder in Rwandan immigrants in Uganda. Cryoglobulins, consisting of IgM, IgG, and to a lesser extent IgA and complement (C3) were identified in the sera of all members of an immigrant Rwandan community with idiopathic splenomegaly, but not in tribe-matched neighbour controls. A significant quantitative relationship was established between cryoglobulin concentration, elevated serum IgM levels, and splenic volume. Cryogobulins did not contain malarial antigen or antibody. Rheumatoid factor-like activity was detected in the sera of patients with splenomegaly and controls and also in the majority of cryoglobulins. Immunofluorescent analysis revealed IgM (and to a lesser extent IgG and C3) in the Kupffer cells and macrophages of the hepatic sinusoids in patients with splenomegaly but not in controls. It is postulated that tropical splenomegaly syndrome results from prolonged stimulation of the reticuloendothelial elements of the liver and spleen by circulating macromolecular immune complexes.