Further description of early clinically silent lupus nephritis.

Thirty silent lupus nephritis (SLN) patients were compared to 16 individuals bearing overt lupus nephritis (OLN). Results included: years of systemic lupus erythematosus (SLE) diagnosis were significantly earlier (4.6 +/- 2.8 years) in SLN than in OLN (7.18 +/- 3.61) (P < 0.05). Neurological compromise, hypertension, normocitic anemia and lymphopenia were significantly prevalent in OLN than in SLN (P < 0.05). Beside normal urinary sediment and renal function tests, the SLN group showed a moderate increase of both activity (AI) and chronicity (CI) renal pathology index when compared to highly increased AI and CI in OLN (P < 0.05). Seventy percent of SLN patients were ISN/RPS Classes I (6.6%) and II (63.3%) while 81% of OLN cases were Classes III, IV (37.5%) and V. IgG, IgA, IgM, lambda chain, C3 and fibrinogen immune deposits were found in 90% or over in both SLN and OLN individuals while in 60% or over, both groups also showed kappa chain, Clq and C4 deposits. While prevalence of ANA, anti-dsDNA and anti-C1q antibodies were similar in both groups, anti-histone, anti-RNP, CIC and CH50 serum levels were significantly different in OLN versus SLN (P < 0.05). We strongly suggest that indeed SLN is the earliest stage in the natural history of lupus nephritis.

Silent nephritis in systemic lupus erythematosus.

Silent lupus nephritis (SLN) was investigated in 42 renal asymptomatic patients and compared with 49 untreated patients with overt lupus nephropathy (OLN). Urinary sediment, quantitative proteinuria, creatinine clearance, antinuclear antibodies (ANA), complement, circulating immune complexes (CIC) and renal biopsies were evaluated in all of the patients. Forty-one out of the 42 (97.6%) patients had SLN according to histopathological findings. Results showed that the mean age, female/male ratio and the clinical activity index (SLEDAI) were similar in both groups (P > 0.05). The prevalence of ANA, anti-ds DNA, anti-ENA autoantibodies and C4 serum levels showed no statistical differences between the two groups (P > 0.05). Conversely, in the OLN group, elevated CIC and diminished CH50 and C3 serum levels were significantly different (P < 0.01). WHO class II was the predominant renal lesion in the group with SLN (P < 0.0001), whereas class IV was in the OLN patients (P < 0.0001). We conclude that, in our series, SLN was highly prevalent in renal asymptomatic patients with otherwise systemic lupus erythematosus. Furthermore, abnormal levels of CIC, CH50 and C3 associated with WHO class II suggest a moderate but ongoing activation of immune-mediated renal injury mechanisms.

Pathology of interstitial nephritis induced in guinea pigs by exoantigens.

Histological and immunofluorescent assessment of the kidney, renal core cultures, and determination of circulating antibodies were carried out in Hartley guinea pigs with a selective delayed-type hypersensitivity state (DTH) and acute interstitial nephritis induced and elicited by exoantigens. The results show that the normal tubule-vascular structure of the kidney, the simplicity of the molecular structure of the exoantigens and the modification of the native form of the exoantigens, when it is presented to the kidney in the elicitation phase of the DTH reaction, are factors which may reduce the cellular response in the normal renal parenchyma. The cytological events over a 48-hour period are not different to those which have been described in DTH reactions in extrarenal tissues. Exoantigens can induce renal lesions evoking an acute interstitial nephritis picture in animals with selective DTH at a time when there are neither circulating antibodies nor deposition of immunoglobulins or infection in the renal parenchyma.