Detection of mycobacterial DNA in papulonecrotic tuberculid lesions by polymerase chain reaction.

Tuberculids are a heterogeneous group of cutaneous lesions. Recent discoveries of M. Tuberculosis DNA in these lesions by PCR suggest that M. tuberculosis could play a role in their pathogenesis. The aim of this study was to demonstrate the presence of M. tuberculosis DNA by polymerase chain reaction in papulonecrotic tuberculid lesions. Skin biopsy specimens from ten patients with papulonecrotic tuberculid lesions (histopathologic features) were studied. All of them tested solidly positive in a tuberculin intradermal test. A gene-amplification PCR, using primers capable of amplifying DNA in the M. tuberculosis complex, was performed to detect M. tuberculosis DNA in the lesions. A 285-bp sequence specific of M. tuberculosis complex was amplified and confirmed by Southern-blot hybridation with a 32 p 5'-labelled internal probe. No inhibitors were detected in the negative PCR samples. The PCR technique makes the detection of mycobacterial DNA in tuberculids a possibility, and therefore provides a rational basis for antituberculous therapy and for the clinical management of these disorders.

Development of autologous T lymphocytes in two males with X-linked severe combined immune deficiency: molecular and cellular characterization.

We report on two patients affected with severe combined immune deficiency (SCID) with an unusual immunological phenotype and a substantial number of autologous, poorly functioning T cells. Distinct mutations identified at the IL2RG locus in the two patients impaired IL-2-mediated signaling but affected T-cell lymphopoiesis differently, resulting in generation of a polyclonal or oligoclonal T-cell repertoire. These observations add to the growing complexity of the immunological spectrum of SCID in humans and indicate the need for detailed immunological and molecular investigations in atypical cases.

Detection of skewed T-cell receptor V-beta gene usage in the peripheral blood of patients with multiple sclerosis.

The ex vivo analysis of the T-cell receptor V-beta (TCRBV) gene usage by circulating T lymphocytes in Multiple Sclerosis (MS) patients may contribute to understanding disease pathogenesis. In the present study, TCRBV gene usage was analyzed in freshly collected unstimulated peripheral blood mononuclear cells (PBMC) isolated from 40 MS patients and 20 healthy controls. Nine patients presented abnormal repertoires, with expansion of one or more TCRBV segments. Among these patients, six presented expansion of TCRBV9 chain expression, three also having an expansion of TCRBV1, TCRBV11 and TCRBV22 segments. The most frequently observed TCRBV chain expansion, TCRBV9, was further analyzed and identified as polyclonal. Evaluation of clinical variables showed that median disease duration was shorter in patients with TCRBV gene expression abnormalities. Longitudinal evaluation of five patients with a skewed repertoire showed regression of expanded TCRBV chains expression to normal values. These data indicate that certain MS patients have abnormal TCRBV gene expression. Such abnormalities are caused by polyclonal expansions of T lymphocyte subpopulations that use the same TCRBV gene families, are unstable and preferentially observed early in the course of the disease.

Detection of clonal T cell populations with closely related T cell receptor junctional sequences in persons at high risk for human immunodeficiency virus (HIV) infection and in patients acutely infected with HIV.

The T cell repertoires were characterized for CD4+ and CD4 lymphocytes derived from 2 patients with acute human immunodeficiency virus (HIV) infection and from 25 HIV-seronegative persons at high risk for acquiring HIV. Oligoclonal expansions of CD4 cells were detected in the HIV-infected patients and in 2 of 3 uninfected high-risk subjects with a reduced number of CD4+ lymphocytes. Furthermore, nucleotide sequencing revealed that some of the T cell receptor (TCR) beta variable segments (TCRBV), which were highly selected in the high-risk subjects, shared closely related junctional sequences, with the TCRBV predominantly expanded in the HIV-infected patients. Since the likelihood that these similarities occurred by chance is extremely low, these data provide direct molecular evidence in support of several cellular and serologic studies suggesting that some persons remain uninfected despite exposure to HIV.

Missense mutations in the Fas gene resulting in autoimmune lymphoproliferative syndrome: a molecular and immunological analysis.

Programmed cell death (or apoptosis) is a physiological process essential to the normal development and homeostatic maintenance of the immune system. The Fas/Apo-1 receptor plays a crucial role in the regulation of apoptosis, as demonstrated by lymphoproliferation in MRL-lpr/lpr mice and by the recently described autoimmune lymphoproliferative syndrome (ALPS) in humans, both of which are due to mutations in the Fas gene. We describe a novel family with ALPS in which three affected siblings carry two distinct missense mutations on both the Fas gene alleles and show lack of Fas-induced apoptosis. The children share common clinical features including splenomegaly and lymphadenopathy, but only one developed severe autoimmune manifestations. In all three siblings, we demonstrated the presence of anergic CD3+CD4-CD8- (double negative, [DN]) T cells; moreover, a chronic lymphocyte activation was found, as demonstrated by the presence of high levels of HLA-DR expression on peripheral CD3+ cells and by the presence of high levels of serum activation markers such as soluble interleukin-2 receptor (slL-2R) and soluble CD30 (sCD30).

Diagnosis of cutaneous tuberculosis in biopsy specimens by PCR and southern blotting.

AIMS: To evaluate the use of a gene amplification and hybridisation method for detecting mycobacterial nucleic acid as a possible diagnostic method for cutaneous tuberculosis infection. METHODS: Biopsy specimens from 20 patients with various skin conditions of possible tuberculous aetiology were studied. Six patients had ulcerative nodules, seven lupiform lesions, two non-necrotic granulomas, one scrofulous lichen, one impetigo, one erythematosus lesions, one warty lesions, and one suspected tuberculous lipoma. Biopsy specimens were stained using Ziehl-Neelsen stain and cultured in Lowenstein-Jensen medium. DNA was extracted and then amplified by PCR using primers specific for the Mycobacterium tuberculosis complex. Specificity was confirmed by Southern blotting. RESULTS: Of the specimens, 30% were positive for mycobacteria on staining with Ziehl-Neelsen stain, 60% were culture positive and 85% PCR positive. Only 35.2% of specimens were positive with all three techniques. A further 32.5% were both culture and PCR positive. All PCR negative samples were also negative when cultured or stained with Ziehl-Neelsen stain. Of the PCR positive specimens, 29.4% were negative when cultured or stained. CONCLUSIONS: PCR, using suitable primers, is an efficient and sensitive method for the diagnosis of cutaneous tuberculosis.

High prevalence of GB virus C infection in a group of Italian patients with hepatitis of unknown etiology.

Prevalence of the recently discovered GB virus C(GBV-C) was evaluated in a cohort of 49 Italian patients with acute or chronic hepatitis of unknown etiology (non-A-E hepatitis) and in a control group of 100 healthy blood donors. The GBV-C genomes could be detected by polymerase chain reaction (PCR) with reverse transcription in 35% of the acute and 39% of the chronic hepatitis patients; only 1 of the control subjects had a positive response. All PCR products hybridized with a specific probe in a colorimetric assay, and the analysis of the sequences of the amplified cDNAs fully confirmed the specificity of the assay. Furthermore, the alignment of the predicted translation products identified two recurrent amino acid substitutions in 6 patients, suggesting the possible existence of at least 2 different GBV-C subtypes. Thus, GBV-C may be an important agent, contributing, at least in Italy, to a significant number of the cases of hepatitis of unknown etiology.

A case of hypereosinophilic syndrome is associated with the expansion of a CD3-CD4+ T-cell population able to secrete large amounts of interleukin-5.

Interleukin-5 (IL-5) is the major soluble factor able to mediate hypereosinophilia. We report a case of hypereosinophilic syndrome in which the presence of a population of CD3-CD4+ cells able to overproduce IL-5 was shown. The lack of CD3 and TCRAB membrane expression on otherwise phenotypically normal mature T lymphocytes together with the absence of detectable TCRBV mRNA and clonal rearrangement of TCRB gene suggested that the abnormal lymphocyte population was the expression of a peripheral T-cell lymphoma with an indolent clinical course. Peripheral blood lymphocytes enriched in this population were able to secrete high levels of IL-5 but not IL-4, and no IL-2 or interferon-gamma, when stimulated in vitro with phytohemagglutinin and phorbol myristate acetate. The serum contained eosinophil survival factors whose activity was partially neutralized by a specific antihuman IL-5 antibody. This observation further emphasized the relationship between hypereosinophilic syndrome. IL-5, and T-cell lymphoproliferative disorders.

Evidence for antigenic selection of large granular lymphocytes in a patient with Wiskott-Aldrich syndrome.

It is now recognized that CD3+ large granular lymphocyte (LGL) proliferations may be clonally derived from their normal CD3+LGL+ counterpart, but the nature of the pressure responsible for the proliferation of these cells remains unclear. We approached this problem by analyzing the diversity of the T-cell receptor repertoire of LGL developed in different clinical settings. Two of our patients had typical lymphoproliferative disorders. The third case was much more unusual, as the LGL proliferation was associated with a Wiskott-Aldrich syndrome. Our data relative to the patients with the lymphoproliferative disorders only suggest that these LGL were clonally expanded. The data relative to the patient with Wiskott-Aldrich syndrome were more unexpected, as the T-cell repertoire of the LGL appeared to have common features with that of the other T-cell populations analyzed. These LGL were characterized by the clonal expansion of a few TCRBV segments that shared common amino acid motifs in the junctional region of the T-cell receptor. This common pattern of junctional diversity associated with different TCRBV segments is, therefore, consistent with a strong on-going antigenic selection process, possibly related to the pathogenesis of Wiskott-Aldrich syndrome. Furthermore, the finding that the same TCRBV segments were also highly expanded among other T-cell subpopulations questions the malignant nature of this LGL proliferation.

Different TCRBV genes generate biased patterns of V-D-J diversity in human T cells.

The aim of this work was to assess whether each T-cell receptor (TCR) BV segment generates a random pattern of junctional diversity or if, alternatively, biased patterns of V-D-J rearrangements limit the number of available TCR specificities. Detailed molecular analysis of T-cell receptors expressed by lymphocytes was obtained by generating a large number of junctional regions sequences from TCRBV3, TCRBV4, TCRBV5S1, TCRBV12, TCRBV13S2, TCRBV17, TCRBV20, and TCRBV22 variable genes. The > 800 sequences analyzed have allowed the characterization of the recombination frequencies of each germline-encoded V, D, and J segments, as well as of the magnitude of exonucleolytic nibbling and of the number of N nucleotides inserted for each group of TCRB segments. The data obtained indicate that the extent of junctional diversity varies considerably depending on the TCRBV gene implicated in the recombination event, due to the occurrence of skewed patterns of J and D region usage. Furthermore, our results show that "illegitimate" rearrangements occur with unexpectedly high incidence, specifically at the level of TCRBD to TCRBJ joining. These findings provide additional information for a more accurate estimation of the size of the TCRBV repertoire and for understanding the well-established biased pattern of TCRBV expression in humans.

Selection of T lymphocytes in two rheumatoid arthritis patients defines different T-cell receptor V beta repertoires in CD4+ and CD8+ T-cell subsets.

To study the selective pressures responsible for the expansion of T cells in rheumatoid arthritis, we constructed cDNA mini-libraries from purified CD4+ and CD8+ T cells prepared from peripheral blood and from synovial fluids of two rheumatoid arthritis patients. Comparison of these libraries by hybridization with specific probes indicated that V beta 2 and V beta 8 transcripts are selectively enriched in the CD4+ synovial fluid lymphocyte population, while V beta 4 was over-represented among both the CD4+ and CD8+ subsets. The enrichment of V beta 14 and V beta 17 observed in synovial fluid T cells of one patient was, however, selectively confined to the CD8+ T-cell subpopulation. Sequence analysis of several V beta 2, V beta 4 and V beta 8 clones, derived from CD4+ cells, revealed a high degree of heterogeneity in the V beta-D beta-J beta junctions, while a more biased utilization of J segments and a more restricted junctional heterogeneity were observed in V beta 4, V beta 14 and V beta 17 clones derived from CD8+ cells. These data suggest that the disease may be induced by the initial activation of a rather heterogeneous population of T-helper cells that are later responsible for the expansion of a more restricted pool of highly specific effector lymphocytes.

Analysis of amplified T cell receptor V beta transcripts by a non-isotopic immunoassay.

We have recently described a new colorimetric DNA enzyme immunoassay (DEIA) for detecting specific hybrids of complementary nucleic acids. This technology is based on an antibody that selectively recognizes double, but not single stranded DNA and therefore reveals the hybridization event independently from the DNA sequences. Most importantly, the test has an ELISA format and is very rapid and convenient for processing large numbers of samples. In the present report we have adapted this method to reveal the specificity of amplified T cell receptor V beta transcripts. V beta genes were amplified by polymerase chain reaction, using family specific primers and the specificity of the amplified products was determined by Southern blot and by DEIA. Our data demonstrate that DEIA had the same degree of sensitivity and specificity of conventional Southern hybridization. The possibility of analyzing amplified products with the simplicity of a conventional immunoassay should greatly facilitate the analysis of complex multigenic systems such as the T cell receptor and the immunoglobulin repertoire.

Non-radioisotopic methods for DNA probes.

We have recently developed a new colorimetric method, DNA enzyme immunoassay (DEIA), for detecting specific hybrids of complementary nucleic acids. This technology is based on an antibody that selectively recognizes double, but not single-stranded DNA. The molecule does not react with a specific probe immobilized on microwells through an avidin-biotin bridge, nor with non-specific amplified sequences, since they are removed by washing. The antibody reveals the hybridization event, independently of the DNA sequences and, for this reason, the method is broadly applicable and extremely versatile. Although we chose a format based on the immobilization of the probe through an avidin-biotin interaction, DEIA assay can also be applied to other analytical schemes that do not require any modification of the probe. Most importantly, the test has an ELISA format and is rapid and convenient for processing large numbers of samples. This technology has been applied, in our laboratory, to different areas, including virology, genetic and basic immunology. The DEIA assay has been successfully used to detect the presence of hepatitis B (HBV), hepatitis C (HCV) and hepatitis delta virus (HDV) sequences in serum of patients, to discriminate different HLA alleles, to identify mutations in the Cystic Fibrosis gene, and to investigate the role of the T cell receptor in some immunological diseases. The results obtained in all our experiments demonstrated that the advantages offered by the assay do not penalize its analytical performance as compared to conventional Southern blot.

Selective depletion in HIV infection of T cells that bear specific T cell receptor V beta sequences.

The mechanism of T cell depletion during infection with the human immunodeficiency virus (HIV) is unclear. Examination of the repertoire of T cell receptor V (variable) regions in persons infected with HIV revealed the absence of a common set of V beta regions, whereas V alpha usage was normal. The lack of these V beta segments did not appear to correlate with opportunistic infections. The selective elimination of T cells that express a defined set of V beta sequences may indicate the presence of an HIV-encoded superantigen, similar to those encoded by the long terminal repeat of the mouse mammary tumor virus.

An immunoassay for specific amplified HCV sequences.

The direct detection of viraemia could improve greatly the efficacy of presently available assays. Due to its sensitivity, the polymerase chain reaction represents the method of choice for direct detection of viral nucleic acid. However, the clinical application of this method is hampered by the requirement of hybridization with radioactively labelled probes. In this study we demonstrate that HCV cDNA, amplified by the polymerase chain reaction from both liver tissues and sera, can be detected specifically by a new non-radioisotopic method, DNA enzyme immunoassay, that is based on an antibody that selectively recognizes double, but not single-stranded DNA. The assay reveals the hybridization events, independently from the DNA sequences, and therefore can be used with any combination of primers and probes. Most importantly, the method has a conventional ELISA format and is compatible with standard facilities of clinical laboratories. The availability of this new approach for revealing amplified sequences may facilitate greatly the use of PCR as the method of choice for early diagnosis of HCV infection.