Immune complexes in leptospirosis

Recent observations suggest that Lyme disease, a spirochaetal infection with multisystem involvement, is an immune complex disorder. The authors have recently studied the presence of circulating immune complexes (CICs) in eight cases of severe leptospirosis, all due to Leptospira icterohaemorrhagiae . The diagnosis was made by the microagglutination-lysis test on serial serum samples. Immunological mechanisms have been postulated to explain the meningeal involvement which in some patients represents the predominant clinical feature. In the authors' patients, the presence of high concentrations of CICs only during the acute phase of illness seens to confirm that in leptospirosis, as in Lyme disease, immune complex reactions are a significant pathogenetic element.