Nephritic factors comprise a heterogeneous group of autoantibodies against
neoepitopes generated in the C3 and C5 convertases of the complement system,
causing its dysregulation. Classification of these autoantibodies can be clustered
according to their stabilization of different convertases either from the classical or
alternative pathway. The first nephritic factor described with the capacity to stabilize
C3 convertase of the alternative pathway was C3 nephritic factor (C3NeF). Another
nephritic factor has been characterized by the ability to stabilize C5 convertase of the
alternative pathway (C5NeF). In addition, there are autoantibodies against assembled
C3/C5 convertase of the classical and lectin pathways (C4NeF). These autoantibodies
have been mainly associated with kidney diseases, like C3 glomerulopathy and immune
complex-associated-membranoproliferative glomerulonephritis. Other clinical situations
where these autoantibodies have been observed include infections and autoimmune
disorders such as systemic lupus erythematosus and acquired partial lipodystrophy. C3
hypocomplementemia is a common finding in all patients with nephritic factors. The
methods to measure nephritic factors are not standardized, technically complex, and
lack of an appropriate quality control. This review will be focused in the description of the
mechanism of action of the three known nephritic factors (C3NeF, C4NeF, and C5NeF),
and their association with human diseases. Moreover, we present an overview regarding
the diagnostic tools for its detection, and the main therapeutic approach for the patients
with nephritic factorsThis work was supported from Instituto de Salud Carlos
III (ISCIII, Ministerio de Economía y Competitividad) and
Fondos FEDER (PI15-00255 to ML-T and PI16-00723 to PS-C).
ML-T). MO was supported by National Science Centre (Poland)
grant 2015/18/M/NZ6/00334
