Recurrent and de novo glomerulonephritis is an important cause of renal allograft failure, but estimates of its prevalence vary widely. One reason for such variability is the inconsistency with which electron microscopy and immunofluorescence are used in assessing renal allograft biopsies.
To determine the prevalence of immune-complex deposits in all renal allograft biopsies performed during a 1-year period and to correlate their presence with clinical data.
Our center accessioned a total of 118 renal allograft biopsies during 1 year from 88 patients. All biopsies were examined by both electron microscopy and immunofluorescence in addition to conventional light microscopy. Patient and donor characteristics were obtained as well as follow-up data for a minimum of 26 months after the index biopsy.
Eight cases of immunoglobulin (Ig) A nephropathy were found (recurrent in 7 and de novo in 1). There were 9 instances of what we designate "IgM-positive immune deposits" without specific features of a recognized glomerulonephritis. To the best of our knowledge, the latter has not hitherto been described and may be part of a heterogeneous group of glomerulopathies. Other unexpected findings included de novo fibrillary glomerulonephritis and de novo membranous glomerulonephritis, the latter occurring at 3 months after engraftment.
A high proportion (19.5%) of unselected renal allograft biopsies show immune-complex deposits both with and without a recognized glomerulopathy. These require both electron microscopy and immunofluorescence for detection. IgM-positive deposits of uncertain etiology are relatively frequent.