Meningococcal meningitis associated with persistent hypocomplementaemia due to circulating C3 nephritic factor.

Two teenage patients who presented with meningococcal meningitis were found to have persistently low C3 levels even after recovery. This was accompanied by circulating C3 nephritic factor, which persisted for more than 12 months in each case. Neither patient had evidence of partial lipodystrophy or of glomerulonephritis initially, although one patient subsequently developed mesangioproliferative glomerulonephritis following a second admission with pneumococcal pneumonia. It is possible that the generation of the nephritic factor was initiated during the presenting illness.