Autologous immune complex nephritis associated with sickle cell trait: diagnosis of the haemoglobinopathy after renal structural and immunological studies.

A renal tubular epithelial antigen (RTE)--anti-RTE autologous immune complex nephritis associated with sickle cell anaemia (SS) has been reported, but immune complex nephritis has never been described in patients with sickle cell trait (SA). During investigation of a child with "asymptomatic proteinuria" cryoprecipitable complexes of RTE-anti-RTE were detected in the serum and granular deposits of RTE, immunoglobulins, and complement localised on the glomerular basement membranes. Morphological and ultrastructural studies showed increased mesangial matrix, sickled red blood cells in the glomeruli and vessels, and tubular and interstitial abnormalities. These findings prompted haemoglobin electrophoretic studies, which showed previously undiagnosed haemoglobin SA in this patient and her family. These observations suggest that nephritis mediated by similar immunopathogenic mechanisms may be associated with SS and SA haemoglobinopathy. Under some conditions patients with sickle cell trait may experience haemodynamic and oxygenation abnormalities, which may be aetiological factors in the immune complex nephritis associated with SS disease.