Crescentic glomerulonephritis, which is sometimes called rapidly progressive glomerulonephritis, is a type of nephritic syndrome, meaning it involves inflammation of the kidney’s glomeruli.
This inflammation ultimately causes a proliferation of cells in the Bowman’s space, which forms a crescent shape and this change leads to renal failure relatively quickly—within weeks to months.
The development of crescents in Bowman’s space can happen in several ways.
In some cases it’s the idiopathic, meaning there’s no identifiable cause.
When the cause is identifiable, though, it can be split into several types.
Type I is caused by anti-glomerular basement membrane, or GBM, antibodies, antibodies that target the GBM.
Type I is associated with Goodpasture syndrome, which also involves pulmonary hemorrhages.
Type II is immune-complex-mediated, meaning caused by immune complexes, composed of antigens and antibodies.
This might be the case with poststreptococcal glomerulonephritis, systemic lupus erythematosus, IgA nephropathy, and Henoch-Schonlein purpura.
And finally type III is known as pauci-immune, meaning little or no anti-GBM antibodies or immune-complex deposits.
In these cases, often anti-neutrophilic cytoplasmic antibodies or ANCAs are in the blood, which are autoantibodies against the body’s own neutrophils.
Furthermore, you can break it down into the type of ANCA. C-ANCAs, or cytoplasmic ANCAs, are associated with Wegener granulomatosis.
P-ANCAs or perinuclear ANCAs on the other hand are associated with microscopic polyangiitis and Churg-Strauss syndrome, the latter of which can be distinguished by having granulomatous inflammation, which is when immune cells attempt to wall off a substance perceived as foreign, asthma, and eosinophilia
Whatever the underlying cause is, the common feature is severe glomerular injury and the development of a crescent shape.
Typically, as a result of cell-mediated immunity as well as macrophage involvement, the glomerular basement membrane breaks.