Sensitivity and specificity of immunological methods for the detection of anti-topoisomerase I (Scl70) autoantibodies: results of a multicenter study. The Italian Society of Laboratory Medicine Study Group on the Diagnosis of Autoimmune diseases

BACKGROUND

The ability of immunometric methods to identify anti-topoisomerase I (Scl70) antibodies is controversial. We wished to quantify the performance of the currently available commercial systems for the assay of anti-topoisomerase I antibodies in a large multicenter study.

METHODS

Fifty Italian clinical laboratories analyzed 36 serum samples: 27 from individuals with scleroderma/systemic sclerosis, and 9 from a control group. The scleroderma/systemic sclerosis samples were positive in our laboratories by both ELISA and immunoblot (IB), and the control samples were negative. The laboratories used 42 immunoenzymatic (ELISA), 21 IB, 3 counterimmunoelectrophoresis, and 2 dot-blot methods, produced by 23 different manufacturers.

RESULTS

We obtained 2389 results. The ELISA methods showed 99.2% specificity and 97.2% sensitivity for detection of anti-Scl70 antibodies. For IB methods, specificity was 97.6% and sensitivity was 96.1%. The Western-blot method had poor analytical specificity (27% false positives for anti-extractable nuclear antigen antibodies other than anti-Scl70).

CONCLUSIONS

Excluding Western blots, commercial ELISA and IB reagents as used in clinical laboratories have a sensitivity and a specificity >95% for determination of anti-Scl70 antibodies.

[Detection of anti-ENA autoantibodies in patients with systemic connective tissue diseases. Analytical variability and diagnostic sensitivity of 4 methods]

This study was designed to assess the analytical sensitivity and rate of agreement between commercial methods and reagents, among the most used in Italy for the detection of autoantibodies to extractable nuclear antigens (ENA). Sixty-eight serum samples from patients with clinically diagnosed systemic rheumatic diseases were aliquoted and distributed to 4 hospital laboratories; three ELISA (Elias, Shield, Inova) and 1 immunoblot method (Euroimmun) were used. Overall agreement between the test reagents, for each anti-ENA specificity, was 69.1% for Ro/SSA, 83.3% for La/SSB, 70.6% for RNP, 73.5% for Sm, 91.1% for Jo1, and 82.3% for Scl70. Lack of specificity (i.e., false positive reactions) was the most important cause of low concordance. When the data were analysed according to the clinical diagnosis, total agreement and specificity improved. However, a significant difference in terms of sensitivity was observed in the SLE group (30 sera) for RNP (positivity ranged from 20% to 43%) and for Sm (from 7% to 37%), and in the Sjögren's syndrome group (13 sera) for anti-La/SSB (from 8% to 38%). Comparable data were obtained for anti-Ro/SSA (from 70% to 77%) both in the SLE and the Sjögren's syndrome group. Sensitivity of all 4 reagents was good in detecting anti-Scl70 autoantibodies in the 8 patients with diffuse systemic sclerosis, as well as anti-Jo1 autoantibody in the 5 polymyositis patients, with a 100% and a 95% agreement, respectively. These data suggest the need of a better standardization of commercial reagents and analytical procedures, and the opportunity that every laboratory should perform anti-ENA determination by at least two different methods, since none of the methods tested was completely reliable in detecting all anti-ENA autoantibody specificities.

Phenotypic characterization of immunomagnetically purified umbilical cord blood CD34+ cells

This study describes the multilineage differentiation pattern of purified CD34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic purification, cells were double stained with anti CD34 and CD71, CD61, CD7, CD19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analysis were performed using a FACScan flow cytometer. After purification, the mean CD34+ cells' purity was 85.49 +/- 7.08%. Several subpopulations of umbilical cord blood CD34+ cells were identified indicating different lineage commitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 +/- 3.76%), while those lacking CD38 were 3.43 +/- 2.12% (CD38-DR+) and 1.81 +/- 1.54% (CD38-DR-). These data were compared to the expression of lineage commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+) and CD34+CD38-DR- cells was significantly lower than umbilical cord blood, 0.24 +/- 0.18% and 0.04 +/- 0.03% respectively. The knowledge and standardized of umbilical cord blood CD34+ cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype suggests that monitoring of lineage differentiation antigens may not be relevant for clinical use of umbilical cord blood samples. However, the observed higher percentage of pluripotent CD34+38- stem cells in umbilical cord blood compared to peripheral blood, that might explain the successful clinical use of umbilical cord blood even when low number of cells are used, candidates these antigens as the predictive parameter for clinical use of umbilical cord blood samples.

Age-related persistent clonal expansions of CD28(-) cells: phenotypic and molecular TCR analysis reveals both CD4(+) and CD4(+)CD8(+) cells with identical CDR3 sequences

In a small group of subjects we had identified persistent expansions (range 6-72%) of CD4(+)CD8(+) double-positive (DP) peripheral blood (PB) cells which express the CD8 alpha/alpha homodimer. Here, DP cells present in a larger cohort were further investigated and found by FACS analysis to express a single or a dominant TCRBV family. In these subjects, with a mean age of about 64 years, expansions of CD4(+) cells with the same TCRBV family specificity as in the respective DP cells also were consistently detected. TCR heterogeneity of the dominant TCRBV family was specifically evaluated: The amplified CDR3 region was cloned and found to consist of one single or two largely dominant sequence patterns. Furthermore, cloning of the CDR3 region from FACS-sorted DP, CD4(+), or CD8(+) cells indicates that both DP and CD4(+), but not CD8(+) cells, isolated from the same individual possess a striking identity of the CDR3 regions. As indicated by FACS analysis, the clonally expanded cells occur in the CD4(+)CD28(-) cells. Taken together, these results suggest that expanded CD4(+)CD28(-) cells might also acquire CD8 alpha/alpha expression and become DP and imply that CD4 clonality is a more frequent phenomenon than previously suspected. In conclusion, the persistent expansions described in this report represent a novel group of age-related benign clonal expansions of still undefined significance of a rare CD28(-) T cell subset.

Variability between methods to determine ANA, anti-dsDNA and anti-ENA autoantibodies: a collaborative study with the biomedical industry

This study was performed by the Italian Society of Laboratory Medicine (SIMeL) in order to establish the variability between the different analytical systems currently used in clinical laboratories for the detection of autoantibodies diagnostic of systemic autoimmune disease. Sixteen industrial, and two university laboratories participated in this study which entailed the determination of anti-nuclear (ANA), anti-dsDNA and anti-ENA antibodies in 11 sera from patients with clinically diagnosed systemic rheumatic disease, using reagents produced by these companies and different methodologies (indirect immunofluorescence, immunoenzymatic assay, counterimmunolectrophoresis, immuno and western blotting). We found 93.5% agreement between the methods used for the detection of ANA, 85.2% for anti-dsDNA antibodies, and 86.9% for anti-ENA antibodies. Among the anti-ENA antibodies, regardless of the method used, detection percentages were excellent for anti-RNP and anti-SSB/La (100%), good for anti-SSA/Ro (93%), but unacceptable for the anti-Jo-1 (67%), anti-Scl70 and anti-Sm (47%) antibodies. This further stresses the need for rigorous standardisation of commercial reagents and analytical procedures, as well as the introduction of external quality assessment (EQA) programs, and a complete definition of operative protocols adjusted to the sensitivity and specificity of the various methods.

CD4 cytopenia and occasional expansion of CD4+CD8+lymphocytes in Sjögren's syndrome

OBJECTIVES

To define whether Sjögren's syndrome (SS) patients have lymphocytopenia compared to healthy controls, and to assess which lymphocyte subset might be involved. The presence of any concurrent infection was recorded.

METHODS

A cohort of ten consecutive patients with SS was studied, and the results were compared with ten sex- and age-matched controls (C).

RESULTS

In SS, a significant cytopenia of CD4+ (679 +/- 339 vs 1110 +/- 222 cells/mm3, p < 0.005) and an even more impressive decrease in the CD4+CD45 RA+ (242 +/- 154 vs 491 +/- 190 cells/mm3, p < 0.005) subset was observed. An absolute CD4 lymphocytopenia (CD4+ < 300 cells/mm3) was seen in two patients. In one patient an unusual finding was the expansion of a double positive population of CD4+CD8+ lymphocytes. No striking relationship with any particular infection was shown. A retrospective review of the absolute CD4+ cytopenia in 54 consecutive SS cases revealed a prevalence of 5.5%.

CONCLUSION

Some SS patients have T lymphocytopenia which mainly affects the CD4+CD45 RA+ subset. Occasional cases with absolute CD4 lymphocytopenia may also be observed. These patients show some evidence of mild recurrent or chronic, but never severe, opportunistic infections.

Monitoring clonal expansion in the laboratory

The definitive demonstration of the clonal origin of an expanded B or T cell population is achieved by the molecular analysis of B or T cell receptor gene rearrangement. However, in recent years techniques that are both sensitive and relatively easy to carry out have been introduced as the first step to the diagnosis of clonality. These include immunochemical analysis of serum and urine to characterize their monoclonal immunoglobulin components, and immunophenotypic studies of peripheral blood or tissue cells. The most widely used techniques are reviewed here, with particular emphasis on the clinical applications of immunofixation electrophoresis and multiparametric cytofluorimetric procedures.

Phenotypic heterogeneity of persistent expansions of CD4+ CD8+ T cells

A group of 18 individuals is described that manifest persistent (follow up between 4 and 57 months) expansions (ranging from 10 to 70%) of CD4+ CD8+ peripheral T cells. In nine individuals there was no apparent underlying disease whereas the remaining displayed a wide range of unrelated diseases. Analysis of the cell surface immunophenotype showed that all individuals express high densities of CD2, CD3, CD5, and TCR alpha/beta on their CD4+ CD8+ subset. On the contrary, these cells did not express CD25, CD38, CD71, HLA-DR, and the beta chain of the interleukin-2 receptor (p75) but expressed high density of CD29 and low density or absence of CD7. CD8 was "dim" in most individuals and consisted only of the CD8 alpha chain isoform. These individuals could be further divided into two subgroups based on the following parameters: in eleven cases CD4+ CD8+ cells had an LGL morphology and expressed the CD11b, CD56 and CD57 NK-associated antigens; in addition, a high percentage of CD4+ CD8- cells from the same individuals also expressed NK-associated antigens on their cell surface (subgroup A). The CD4+ CD8+ cells of the remaining individuals had small lymphocyte morphology, expressed little or no CD11b and CD56 and their CD4+ CD8- cells did not express NK-associated antigens at all (subgroup B). Finally, CD8 was "bright" on the CD4+ CD8+ cells of three individuals and in these cells also the CD8 beta chain isoform was present (subgroup C). Southern blot hybridization of genomic DNA with a T-cell receptor beta probe revealed that of the sixteen individuals examined four had a monoclonal, seven an oligoclonal, and five a polyclonal molecular configuration. The present data indicate that persistent CD4+ CD8+ expansions represent a novel heterogeneous subset of T cells.

Persistent expansions of CD4+ CD8+ peripheral blood T cells

CD4+ CD8+ cells are present during T cell differentiation in the thymus. Less than 2% of normal T cells that coexpress CD4 and CD8 also are released in the circulation and are present in the peripheral blood. In this study, nine individuals are described that manifested persistent expansions (11% to 43%) of circulating CD4+ CD8+ T cells that in three cases had large granular lymphocyte (LGL) morphology in the absence of either lymphocytosis or overt lymphoproliferative disorders. Southern blot hybridization of enriched CD4+ CD8+ cells with T-cell receptor beta (TCR beta) and TCR gamma probes showed that most cases had the 12-kb Eco RI germinal band deleted or of decreased intensity. In several individuals new TCR beta-specific bands of different intensity and distinct from case to case suggested either monoclonal or oligoclonal and polyclonal expansions. Immunophenotypic analysis showed that in 7 out of 9 cases the CD4+ CD8+ T cells presented with CD8 dim expression. Furthermore, all the CD4+ CD8+ cells did not express many of the known activation antigens (low or absent CD25, CD38, CD71, HLA-DR), whereas they expressed high levels of CD2, CD29, CD56, and CD57. In addition, the CD4+ CD8+ cells of 5 out of 9 subjects coexpressed CD45RA and CD45RO suggesting that these cells might be "frozen" in an intermediate state between naive and memory T cells. In conclusion, the present CD4+ CD8+ cases fall within a larger spectrum of disorders ranging from apparently normal to reactive or proliferative situations and encompassing cells with LGL morphology or LGL-associated antigens expression either in the presence or in the absence of absolute lymphocytosis that deserve careful follow-up investigations.

Inappropriate emergency test ordering in a general hospital: preliminary reports

An assessment was made on emergency laboratory test ordering at Udine General Hospital (Italy) to investigate the reasons for the excessive number of requested tests. All the orders for emergency laboratory tests during one week in June 1990 were studied. For each test the time of the order was recorded for every day of the week. The most important aspect of our investigation is the distribution of the orders during the day: in fact, test orders reached two peaks, the upper between 7 and 11 a.m., and the lower between 3 and 6 p.m. The analysis of the record cards showed that 42% of the orders were inappropriate. These preliminary findings were very useful in making the consensus on a Quality Assurance program easier, to improve the use of the Emergency Laboratory by doctors and nurses. Some preliminary results in the Emergency Medicine Department confirmed the validity of this program.

[Influence of radiotherapy on lymphocyte subpopulations]

The authors investigated the effects of radiation therapy on the immune system by studying lymphocyte subsets and other parameters in 32 patients undergoing radiation therapy for solid cancer. With monoclonal antibody techniques, we studied both T- and B-lymphocytes; cell suspensions were analyzed by means of a Facs Spectrum III Ortho (Ortho-Diagnostic) unit. The first control was performed right after the beginning of radiotherapy, when the dose to the patients was 50 Gy or higher. The second control was performed at 40 Gy because all patients received this dose. 30% of the patients exhibited lymphopenia from the beginning of the study; at 40 Gy the number of T-lymphocytes was low and helper/suppressor ratio was altered. A variable response of B-cells was observed, although all patients exhibited restoration of normal values at 6 months. Four patients only suffered from side-effects: a patient with tongue cancer presented oral mycosis, and a woman--treated for breast cancer--presented vaginal mycosis. Two cases of cystitis were also observed, after 18 Gy, in patients with uterine carcinoma undergoing pelvic irradiation. Disease progression was observed in 2 patients with head and neck cancer, while 3 patients died from lung cancer progression. Another one, with head and neck cancer, died because of heart failure.

Immunochemical and structural characterization of an IgG1 heavy chain disease

The immunochemical and structural analysis of an IgG1 heavy chain disease is reported. The abnormal component is characterized by extensive deletion including the CH1 domain and most or all of the VH region.

[B lymphoproliferative syndrome with characteristics common to chronic lymphatic leukemia, Waldenström disease and plasmacytic leukemia]

A case of lymphoproliferative disorder presenting some features of chronic lymphocytic leukemia, Waldenström's disease and plasmacell leukemia without the full diagnostic criteria of any of these diseases is reported. It clearly demonstrates the affinity existing among the various neoplasms of the B-lymphocyte cell line.

Alpha-heavy chain disease. Report of a case with spontaneous regression

The occurrence of alpha-heavy chain disease in an Italian adult, working in Libya, is reported, characterized by a spontaneous clinical and immunological recovery. It is suggested that the patient could have acquired the disease during his stay in an endemic area of alpha-heavy chain disease, and that the observed spontaneous remission could be related to the removal of environmental pathogenic factors, following his departure from Libya.

[T lymphocyte subpopulations in rheumatoid arthritis]

The study of T lymphocyte subpopulations defined by monoclonal antibodies in a group of patients with rheumatoid arthritis and a control group indicated no significant differences in the percentages of total T lymphocytes (OKT3+) or helper-inducer lymphocytes (OKT4+). However there was a significant diminution in suppressor-cytoxic lymphocytes (OKT8+) in patients with active forms of the disease. This diminution led to an increase in the proportion of OKT4+/OKT8+ in patients with active R.A. forms compared to both those in remission and the control group.

[Spermatogonia counts in descended and undescended prebuberal testes (author's transl)]

The following conclusions which show the importance of time of medical treatment resulted from the examination of 288 testicular biopsies (including 46 controls) by statistical analysis in correlation to age. 1. There is no difference in the number of spermatogonia per tubule cross section of descended and undescended testes in children from birth to 2 years of age. 2. The number of spermtogonia in descended testes is not different in children from birth to 2 years in comparison to children aged 2-6 years. 3. A statistically significant decrease of spermatogonia takes place in the undescended testes of children from 2-6 years in comparison to children from birth to 2 years. 4. The difference in the number of spermatogonia of descended and undescended testes increases in children above the age of 2. It must be concluded from this study that the pathological alterations of the germinative epithelium increase in children beyond the age of 2. Assuming that pathological alterations of the germinative epithelium are caused by the dystopy of the testes, medical treatment should be carried out before the child is more than 2 years old.