Manuela Colucci1, Barbara Ruggiero2, Alessandra Gianviti2, Maria Manuela Rosado3, Rita Carsetti3, Claudia Bracaglia4, Fabrizio De Benedetti4, Francesco Emma2, Marina Vivarelli2. 1. Renal Diseases Research Unit, Genetics and Rare Diseases Research Area, Bambino Gesù Children's Hospital, IRCCS, Viale S. Paolo 15, 00146, Rome, Italy. manuela.colucci@opbg.net. 2. Division of Nephrology, Department of Pediatric Subspecialties, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy. 3. B Cell Pathophysiology Unit, Immunology Research Area, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy. 4. Division of Rheumatology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
Abstract
BACKGROUND: Children with systemic lupus erythematosus (SLE) frequently have kidney involvement. Lupus nephritis sometimes presents alone, without systemic SLE features, representing the so-called full-house nephropathy (FHN). Distinguishing patients with SLE or FHN has therapeutic and prognostic implications. METHODS: In this retrospective observational study, we determined the presence of IgM on the surface of T cells (T cell IgM) by flow cytometry and characterized its ability in distinguishing SLE and FHN patients in a large pediatric cohort (n = 84). Fifty-seven patients with SLE (≥ 4 SLICC criteria at disease onset or during the follow-up) and 27 patients with FHN (3 or less SLICC criteria) were enrolled. RESULTS: Elevated T cell IgM levels were found in 24/25 SLE patients in active phase of disease and in 29/45 SLE patients in remission. In contrast, among FHN patients, only 1/9 presented this characteristic in active phase of disease and 0/20 in remission. Compared with standardized SLICC laboratory parameters, i.e., autoantibody titers and hypocomplementemia, T cell IgM positivity showed an extremely high sensitivity and specificity for the diagnosis of SLE, with the highest area under the curve (0.97, p < 0.001) by receiver operating characteristic analysis, similar to ANA (0.96, p < 0.001) and anti-dsDNA (0.90, p < 0.001) autoantibodies. CONCLUSIONS: Altogether, our data indicate that T cell IgM intensity may be a useful tool to correctly classify patients with lupus nephritis as SLE or FHN since disease onset.
BACKGROUND: Children with systemic lupus erythematosus (SLE) frequently have kidney involvement. Lupus nephritis sometimes presents alone, without systemic SLE features, representing the so-called full-house nephropathy (FHN). Distinguishing patients with SLE or FHN has therapeutic and prognostic implications. METHODS: In this retrospective observational study, we determined the presence of IgM on the surface of T cells (T cell IgM) by flow cytometry and characterized its ability in distinguishing SLE and FHN patients in a large pediatric cohort (n = 84). Fifty-seven patients with SLE (≥ 4 SLICC criteria at disease onset or during the follow-up) and 27 patients with FHN (3 or less SLICC criteria) were enrolled. RESULTS: Elevated T cell IgM levels were found in 24/25 SLE patients in active phase of disease and in 29/45 SLE patients in remission. In contrast, among FHN patients, only 1/9 presented this characteristic in active phase of disease and 0/20 in remission. Compared with standardized SLICC laboratory parameters, i.e., autoantibody titers and hypocomplementemia, T cell IgM positivity showed an extremely high sensitivity and specificity for the diagnosis of SLE, with the highest area under the curve (0.97, p < 0.001) by receiver operating characteristic analysis, similar to ANA (0.96, p < 0.001) and anti-dsDNA (0.90, p < 0.001) autoantibodies. CONCLUSIONS: Altogether, our data indicate that T cell IgM intensity may be a useful tool to correctly classify patients with lupus nephritis as SLE or FHN since disease onset.