Autoantibodies and autoantigens in the urine of SLE patients.

Autoantibodies against RNA polymerase I (RNAPI), DNA, La and ribosomal P proteins were detected in the urine of systemic lupus erythematosus (SLE) patients, many with normal protein excretion rates. In a number of cases, the antibodies were detectable in the urine but not the serum sample of the same patient. The presence and relative concentrations of the urinary autoantibodies correlated with disease activity. RNAPI antigens were detected in the urine of SLE patients by radioimmunoassay and immunoblotting using rabbit antisera prepared against the purified holoenzyme. Immunoaffinity purification of the rabbit anti-RNAPI with SLE urine proteins resulted in antibodies directed primarily against the largest RNAPI subunit (S1; 194 kDa). Antibodies prepared against recombinant fusion proteins representing the DNA binding regions of human RNAPI(S1) reacted with a 35 kDa SLE urinary protein, a putative fragment of RNAPI(S1). Ribosomal protein P0 was detected in SLE patients' urine by immunoblotting, using rabbit antiserum prepared against recombinant human P1 fusion protein. The relative quantities of urinary P0 correlated with disease status. Analysis of urinary autoantibodies and corresponding antigens in conjunction with analysis of serum autoantibodies may be of value for the purpose of monitoring disease activity.

Measurement of urinary S100B protein concentrations for the early identification of brain damage in asphyxiated full-term infants.

BACKGROUND: Perinatal asphyxia is a major cause of mortality and morbidity. To date there are no reliable methods to detect which infants will develop brain damage after asphyxia insult. We investigated whether measurements of urine levels of S100B in asphyxiated full-term newborns may be a useful tool for early detection of postasphyxia brain damage. METHODS: A prospective study of 38 infants with perinatal asphyxia and 96 control subjects, recruited at 3 tertiary departments of neonatology between April 1, 1999, and July 31, 2001. Routine laboratory variables, neurologic patterns, and urine concentrations of S100B protein were determined at 4 predetermined time points (first urination and 12, 24, and 72 hours after birth). The concentrations of S100B protein in urine were measured using an immunoluminometric assay. The results were correlated with the presence or absence of neurologic abnormalities at age 12 months. RESULTS: S100B protein levels were significantly higher in samples collected at all monitoring times from new-borns with abnormal neurologic findings on follow-up (first urination, 1.92 +/- 0.33 micro g/L; 12 hours, 2.78 +/- 1.71 micro g/L; 24 hours, 4.75 +/- 4.08 micro g/L; 72 hours, 5.93 +/- 1.63 micro g/L) than in samples from those without (first urination, 0.24 +/- 0.06 micro g/L; 12 hours, 0.13 +/- 0.06 micro g/L; 24 hours, 0.21 +/- 0.07 micro g/L; 72 hours, 0.12 +/- 0.04 micro g/L) or from healthy infants (first urination, 0.11 +/- 0.01 micro g/L; 12 hours, 0.12 +/- 0.03 micro g/L; 24 hours, 0.12 +/- 0.02 micro g/L; 72 hours, 0.12 +/- 0.02 micro g/L) (P<.001 for all). An S100B concentration cutoff of 0.28 micro g/L at first urination had a sensitivity of 100% and a specificity of 87.3% for predicting the development of abnormal neurologic findings on follow-up. The sensitivity and specificity of measurements obtained between 12 and 72 hours were up to 100% and 98.2%, respectively. CONCLUSION: Longitudinal S100B protein measurements in urine soon after birth are a useful tool to identify which asphyxiated infants are at risk of long-term neurologic sequelae.

Mucosal immunity and primary biliary cirrhosis: presence of antimitochondrial antibodies in urine.

We have shown that IgA-class antimitochondrial autoantibodies (AMA) can be detected in the bile and saliva of patients with PBC, suggesting that AMA are secreted into the luminal fluid across bile ducts and salivary glands. These data prompted us to determine whether AMA of the IgA isotype may be transported across other epithelial mucosa. Therefore, we tested for the presence of AMA in the urine specimens of 83 patients with PBC and 58 non-PBC controls including healthy individuals and patients with other liver diseases. Patients enrolled in this study had no history of renal disease, and we confirmed there was less than 50 microgram/mL of protein in each of the urine specimens. Interestingly, we found that AMA were present in the urine of 71/83 (86%) of all patients with PBC and in 71/78 (91%) of patients with PBC that were serum AMA positive. In contrast, AMA were not detected in any of the 58 control urine specimens. Of particular interest, AMA of the IgA isotype was present in 57/83 (69%) of patients with PBC, and in 52 of these 57, we found secretory-type IgA. In a nested random subgroup of urine samples, the prevalence of the IgA2 AMA was 6/18 (33%), significantly lower than in matched serum samples, 13/16 (81%, P =.007). These data show that AMA of the IgA isotype is secreted into urine from the uroepithelium of patients with PBC, and support the thesis that PBC originated from either a mucosal challenge or a loss of mucosal tolerance.

Urine cytology. It is still the gold standard for screening?

Urine cytology remains the gold standard for bladder cancer screening. It is the test against which all others are compared when evaluating potential bladder tumor markers. The answer to whether urine cytology possess the optimal combination of sensitivity and specificity to retain consideration as the best screening device depends on the goals of the clinical practice. Urine cytology has excellent specificity with few false-positive cases. Its overall sensitivity is poor, but this drawback is explained for the most part by poor criteria for identifying well-differentiated, low-grade TCC. The natural history of such lesions is the occurrence of multiple superficial recurrences in 70% to 80% of patients, with only a minority (10% to 15%) progressing to muscle invasive or metastatic disease. Because patients with low-grade TCC are at low risk for progression, they are monitored primarily for the development of a subsequent tumor. One might argue that the detection of new low-grade lesions is of secondary importance to the early detection of disease progression. The performance characteristics of urine cytology in this regard are much improved. Urine cytology often results in the identification of high-grade malignant cells even before a cystoscopically distinguishable gross lesion is present. Routinely diagnosing grade I TCC may be clinically irrelevant. Ancillary techniques to improve the sensitivity of urine cytology have been insufficiently additive to have much clinical value. Several promising bladder tumor markers have been investigated as potential screening tools and are summarized in Table 3. BTA, nuclear matrix proteins, and fibrin/fibrinogen degradation products share lower specificities than urine cytology and may have high rates of false positivity. Telomerase is highly sensitive and highly specific but is not readily available as a point-of-service test. Hyaluronidase and hyaluronic acid are promising prognostic markers, but hyaluronidase does not detect grade I TCC. Early results from studies of this marker await verification. Combining some of these new markers may optimize their performance status, allowing the advantages of one test to correct the shortcomings of another. Likewise, their combination with urine cytology may prove beneficial. Although adding urine cytology has not increased the sensitivity of some point-of-service tests, few studies have addressed the effect on specificity. Until an obvious winner is declared in the race to find a bladder tumor marker, urine cytology will remain the gold standard screening method because of its comfortable familiarity.

Use of urine-based markers for detection and monitoring of bladder cancer.

Diagnosis and monitoring of bladder cancer present a difficult clinical problem. Urine cytology with confirmatory cystoscopy form the cornerstone of diagnosis at the present time. The subjectivity and low sensitivity of cytology led to the development of numerous tests as adjuncts to cystoscopy for the diagnosis and follow-up of bladder cancer patients. These tests usually are objective, quantitative (NMP-22, BTA TRAK, BLCA-4, telomerase activity, etc.), or qualitative (BTA Stat and FDP) and have higher sensitivity than cytology, but some have lower specificity. We review the different, new urine-based tests that were developed recently for the diagnosis and monitoring of patients with bladder cancer. The advantages and disadvantages of these tests are discussed, as well as their possible future role in the management of patients with bladder cancer.

Reversible tubular proteinuria precedes microalbuminuria and correlates with the metabolic status in diabetic children.

Early tubular alterations were studied in 53 children with insulin-dependent diabetes mellitus (IDDM), 32 of whom were followed at regular 6-monthly intervals for 3 years. The urinary levels of retinol-binding protein (RBP), beta 2-microglobulin and brush border antigens (BBA) (determined by monoclonal enzyme immunoassay) were taken as indices of functional and cellular tubular alterations; urinary albumin was considered an early marker of glomerular alterations. All indices of tubular alterations were higher in IDDM children than in 368 normal children, while albuminuria was unchanged. Urinary levels of BBA, however, varied widely during follow-up, with 25 of the 32 IDDM patients who were followed at regular intervals having pathological values for BBA on at least one occasion, followed by normalization. Metabolic alteration was found to be the main cause of this variability, since a high statistical correlation was found between urinary BBA and fructosamine (P < 0.001) and between RBP and the stable fraction of glycosylated haemoglobin (P < 0.001). The data confirm that transient tubular proteinuria occurs in diabetic children before any other marker of renal involvement such as microalbuminuria. The maintenance of good metabolic control is essential to normalize this early abnormality that can be considered a reversible sign of functional renal involvement.

Rapid assay for immune complex bound antigens from urine of cancer patients.

Concentrated urine from patients with various types of cancer was fractionated by S-500 gel filtration chromatography to yield high molecular weight (mw) immune complexes (IC) and lower mw immunoglobulin (Ig) fractions. Column fractions were assayed for the presence of IgM and IgG by immunoblot probing using anti-human IgM and anti-human IgG alkaline phosphatase conjugates. These results were used to define IC fractions (those from high mw S-500 fractions which were positive for immunoglobulin) and Ig fractions (those from medium mw S-500 fractions which were positive for immunoglobulin). Antigen components of high mw S-500 IC fractions were then determined by immunoblot probe using medium mw S-500 Ig fractions as the antibody probe (i.e. autoantibody). This method for identification of immune complex antigens has the potential to probe for tumor-associated antigens, autoantigens, or foreign antigens from starting material which contains both immune complex and free immunoglobulin.

Presence of "rheumatoid neoantigen-like material" in urine of patients with RA, demonstrated by use of leukocyte adherence inhibition assay.

Peripheral blood leukocytes (PBL) from patients with rheumatoid arthritis (RA) when used in the leukocyte adherence inhibition (LAI) assay were capable of distinguishing antigenic differences between rheumatoid and osteoarthritic synovial membrane extracts. The positive LAI response of RA patients was negated by preincubating the cells with sera or urine proteins obtained from LAI nonreactive RA patients. This study suggests that LAI nonreactive RA subjects have in their serum a material cross reactive with rheumatoid synovium which we have called "rheumatoid neoantigen-like material" which is excreted in their urine, and is capable of being recognized by PBL of reactive, LAI positive RA patients.