Proerdin and recurrent macroscopic haematuria.

Kidney biopsies from ten children with recurrent macroscopic haematuria, showed mesangial deposition of IgG, IgA and complement. Eight of these ten biopsies also showed disposition of properdin, a basic euglobulin intimately involved in the alternate pathway of complement activation. Serum haemolytic complement activity was normal in the eight patients tested. Incubation of the serum at 4 degrees C for 24 dours did not result in any change in complement activity. Theses data suggest that the mesangial inflammatory process in these patients may be medicated in part by the alternate pathway of complement activation and that the mechanism is activated locally.