Antibodies to phospholipase-A2 receptor- IgG
Membranous nephropathy marker, necessary to prognose and monitor the treatment.
Antibodies to phospholipase A2 receptor (Anti-PLA2R) are autoantibodies directed against one of the podocyte membrane glycoproteins (PLA2R). They are specific clinical and laboratory signs of idiopathic membranous glomerulonephritis (membranous nephropathy), whereas the part of Anti-PLA2R in this disease pathogenesis remains undetermined at present. Mostly they belong to IgG 4 immunoglobulins.
Membranous glomerulonephritis is the key cause of nephrotic syndrome in adults. In 30% of cases, it is developed in association with any systemic disease (systemic lupus erythematosus, hepatitis B, malignant neoplasms) or drug reaction (non-steroidal anti-inflammatory) and it is secondary. In most cases it is not possible to find out the cause, therefore this form of disease is called primary (idiopathic) membranous glomerulonephritis (IMG). Thus, examination of the patient with nephrotic syndrome, and membranous glomerulonephritis in particular is a complex of laboratory and instrumental tests since idiopathic membranous glomerulonephritis is a “diagnosis of exclusion”. Recently, Anti-PLA2R study has been introduced into the diagnostic algorithm of nephrotic syndrome and IMG.
Antibodies to phospholipase A2 receptor are found in 52-82% of patients with IMG, making them a significant sign of this disease. However, they are not found during secondary membranous glomerulonephritis and therefore they can be taken as specific for IMG. Anti-PLA2R is not found in other forms of glomerulonephritis (IgA nephropathy, focal segmental glomerulosclerosis, lipoid nephrosis). Based on that Anti-PLA2R test can be used for the differential diagnosis of glomerulonephritis and nephrotic syndrome. Anti-PLA2R is not found in the blood of healthy people.
Anti-PLA2R test can be used to prognose the disease. It has been proven that spontaneous disease remission is observed much less frequently in patients with high Anti-PLA2R titer than in patients with low titer of these antibodies (4 versus 38%). Anti-PLA2R test can be used to assess the treatment. Anti-PLA2R titer indicates the disease activity and proteinuria rate. High Anti-PLA2R titer is found in the blood of patients with high disease activity and massive proteinuria. Opposite Anti-PLA2R concentration comes down during treatment and becomes undetectable in the remission time. Recurrence of IMG is associated with Anti-PLA2R titer increase.
Keep in mind that presence of Anti-PLA2R does not substitute the kidney biopsy for the patient with nephrotic syndrome as well as comprehensive examination to exclude the systemic disease for the patient with membranous glomerulonephritis.
Indications for the test
- Nephrotic syndrome symptoms (edema of the lower limbs and periorbital area, ascites, weight gain, daily protein loss of more than 3 g, hypoalbuminemia, hypercholesterolemia);
- Immunohistochemical signs of membranous glomerulonephritis.