Urinary T Lymphocytes Predict Renal Flares in Patients With Inactive ANCA-associated Glomerulonephritis

Data of previous studies have shown that counts of urinary T lymphocyte subsets correlate with disease activity in several immunological renal diseases, e.g. ANCA-associated glomerulonephritis. Thus, study authors hypothesise that CD4+, respectively CD8+, T effector memory lymphocytes found in urine samples of patients with inactive ANCA-vasculitis predict subsequent renal flares. Therefore, quantification of these cellular subsets might reliably predict relapse of ANCA associated glomerulonephritis at an early stage. In a prospective experimental study urine of patients with ANCA-vasculitis and no renal involvement or patients in renal remission will be analysed by flow cytometry. After 6 months of observation, clinical outcome and potential renal relapse will be determined and correlated to initial T lymphocyte count.

Inclusion criteria

• diagnosed ANCA-associated vasculitis (clinical diagnosis of granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis or microscopic polyangiitis consistent with the Chapel-Hill consensus definitions AND positive test for proteinase 3-ANCA or myeloperoxidase-ANCA)
• no currently active renal involvement (defined as BVAS = 0 with exception of hematuria or proteinuria as signs of renal scars)
• written and informed consent

Exclusion criteria

• urinary tract infection
• active menstrual bleeding
• active renal involvement
• other active renal disease (e.g. diabetic nephropathy)

Initially, we defined treatment with rituximab as exclusion criteria. However, upon closer examination, we recognized that this exclusion criterion was overly restrictive and may have inadvertently excluded eligible participants who met our other inclusion criteria. As a result of this reassessment, we have revised our exclusion criteria to no longer exclude individuals solely on the basis of receiving rituximab treatment.