Rheumatoid factors in patients with minimal change nephrotic syndrome.

Several immunological aberrations, especially T-cell abnormalities, have been shown to be involved in the development of the minimal change nephrotic syndrome (MCNS) although the responsible factors have not been identified. We studied rheumatoid factors (RF), thought to be a consequence of polyclonal B-cell hyperactivation, in sera from patients with MCNS using a sensitive fluorescence immunoassay (FIA). Significant increases of IgG and IgM RFs and marginal increase of IgA RF were observed during the nephrotic stages. Some patients still showed high titers of IgM RF in the early remission phases. The levels of RFs were normalized during complete remission. It was suggested that polyclonal B cell activation might be involved in the development of this disorder along with T cell abnormalities.